6. SOLID STATE ELECTROLYTE DEVELOPMENT FOR ADVANCED ENERGY STORAGE DEVICES

The projected doubling of world energy consumption within the next 50 years, coupled with the growing demand for low- or even zero-emission sources of energy, has brought increasing awareness of the need for efficient, clean, and renewable energy sources. In particular, the generation of electricity from renewable sources, such as solar or wind, offers enormous potential for meeting future energy demands. However, these sources are intermittent; therefore, an efficient electrical energy storage (EES) sytem is required to ensure that the electricity is reliably available 24 hours a day, as needed for commercial and residential grid applications. Even short fluctuations can cause changes in supply, which currently must be corrected using conventional power plants. Thus, for large-scale solar- or wind-based electrical generation to be practical, the development of new EES systems will be critical to making renewables dispatchable, meeting off-peak demands, shaving peak loads, and effectively leveling the variable nature of these energy sources.

The objective of this topic is to improve the performance and manufacturability of advanced utility-scale batteries, reduce their negative environmental effects, and ameliorate safety concerns. Improvements in battery performance rely as much on developments in electrolytes as they do on improvements in the active materials themselves. Most current battery cells all contain some form of liquid electrolyte. Often these electrolytes are toxic or flammable, and can cause a variety of problems should leaks occur. If solid state electrolytes could be developed, many of these issues could be alleviated. Solid-state materials having high ionic conductivity (e.g., solid polymer electrolytes) have been the subject of extensive research for select electrochemical power sources for many years. The reasons for this are manifold: anticipated improvements in battery performance, enhanced geometric flexibility (size/shape), ease of manufacture (eg bipolar configurations), and improved safety. Nevertheless, these all-solid-state electrolytes still are not readily available for all battery chemistries.

Grant applications are sought only in the following subtopics:

a. Solid State Electrolyte Development for Lithium-Ion Chemistries—For lithium-ion rechargeable battery chemistries, lithium-ion-conducting materials will be needed as the electrolyte. Therefore, grant applications are sought to develop stable, safe, easy to manufacture, and cost effective solid-state electrolytes for lithium-ion transport for non-aqueous lithium-ion battery chemistries. Approaches leading to all-solid-state systems are preferred, with little (<0.5%) or no additional liquid content (e.g., no plasticizers or co-solvents). Electrolytes of interest must exhibit the requisite properties for use in these battery chemistries, including high room-temperature conductivity, chemical stability, electrochemical stability, thermal stability, and high transport number (ideally equal to 1; that is, a single ion conductor). Proposed solutions must be scalable to utility bulk energy storage systems.

Questions: contact Imre Gyuk (imre.gyuk@hq.doe.gov)

b. Solid State Electrolyte Development for Hydroxyl-Ion Transport in Aqueous Alkaline Chemistries—For alkaline based-systems such as nickel-metal hydride or nickel-cadmium batteries, hydroxyl-ion-conducting materials will be needed for the electrolyte. Therefore, grant applications are sought to develop stable, safe, easy to manufacture, and cost effective solid-state electrolytes for hydroxyl-ion transport for aqueous alkaline battery chemistries. Compared to lithium ion chemistries, higher quantities of water as plasticizer or co-solvent will be allowed. Nonetheless, all-solid-state systems, with little or no additional liquid phase, are preferred. Electrolytes of interest must exhibit proper electrochemical properties for these alkaline systems, including high room-temperature conductivity, chemical stability, electrochemical stability, and high transport number (again, a single ion conductor is preferred). Proposed solutions must be scalable to utility bulk energy storage systems.

Questions: contact Imre Gyuk (imre.gyuk@hq.doe.gov)

References

1 Alasdair M. Christie, et al., “Increasing the Conductivity of Crystalline Polymer Electrolytes”, Nature, 433, 6 January 2005 (Text is for sale at http://www.nature.com/nature/journal/v433/n7021/fig_tab/nature03186_F1.html, click on the title)

2 Jennings, R.A., “Conducting Solids, Covering Ionic and Electronic Conductors”, Annu. Rep. Prog. Chem., Sect. A, 1999, 95, 481-506 (ISSN 0260-1818)

3 Jorne, J. Lett, N., Transference Number Approaching Unity in Nanocomposite Electrolytes, Vol. 6, No. 12, 2006 (http://pubs.acs.org/cgi-bin/abstract.cgi/nalefd/2006/6/i12/abs/nl062182m.html)

4 Zheng, N, Bu, X., Feng, P., “Synthetic Design of Crystalline Inorganic Chalcogenides Exhibiting Fast-Ion Conductivity”, Nature, 426, 27, 2003 (Text is for sale at http://www.nature.com/nature/journal/v426/n6965/fig_tab/nature02159_F1.html, click on title)

5 Tiyapiboonchaiya, C., et al., “The Zwitterion Effect in High-Conductivity Polyelectrolyte Materials”., Nat. Materials, 3, 29, 2004 (Text is for sale at http://www.nature.com/nmat/journal/v3/n1/suppinfo/nmat1044_S1.html, click on title)

6 Alarco, P.J., et al., “The Plastic-Crystalline Phase of Succinonitrile as a Universal Matrix for Solid-State Ionic Conductors,” Nat. Materials, 3, 476, 2004 (Abstract available at: http://www.nature.com/nmat/journal/v3/n7/abs/nmat1158.html)