e d i to ri a l
A Big Energy “Fish” in Need of Some Measurements
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lectrochemical energy storage (EES) science is alive and well but very much in need of some basic developments in measurement science. EES is essential to the energy health of the U.S. and other nations. We citizens are wedded to our portable laptop and cell-phone power sources and expect them to continue to get better. We hear a lot about interest in hybrid electrically propelled cars. There are, however, massively larger and less publicly understood goals for EES, such as peak-shaving and load-leveling in the national electric grid, off-hour storage of solar- and wind-generated energy, recovery of some of the electrical energy consumed in a forklift load during lowering of that load, and improving power quality in our increasingly digital society. To illustrate the importance of power quality, consider that power interruptions— long- and short-term—cost U.S. industry an estimated $79 billion per year. Imagine the angst of the manager of a microchip foundry when the power flickers for even a few seconds! I prepared this Editorial while I was a participant in a workshop on EES, sponsored by the U.S. Department of Energy’s (DOE’s) Basic Energy Sciences program. The workshop was aimed at identifying the technical and basic-science obstacles to improving EES systems, which include electrochemical capacitors (storing charge in the electrical double layer of a highly porous electrode) and batteries. They range from tiny devices in your laptop to barn-sized installations with megawatts of power. The ideal EES device has high voltage, power, and power density; is indefinitely stable, safe, and abuse-tolerant; poses no safety hazard or environmental disposal issues; is lightweight; and can be deployed at low cost. We are very far from that ideal, and the current limitations are a burden on anticipated EES applications. The field seriously needs a better fundamental understanding of the electrochemical processes involved as well as the invention of new cathode, anode, and electrolyte materials. DOE hopes to support such work.
© 2007 AMERICAN CHEMICAL SOCIETY
Not surprisingly, new analytical measurement capabilities emerged as a prime need in fundamental research. The list of questions that need experimental answers is quite long. What happens during an electrochemical discharge; what makes it an efficient process; what causes an electrochemical cell to fail? The analytical advice given was bold: we need experiments that yield compositional and structural information on distances that range from atomistic to microcrystalline and on timescales that range from bond-breaking to hours. How can you detect changes at hidden or buried interfaces while the electrode device is functioning? Can you observe the solvation changes that occur during an electrochemical reaction on informative timescales? What are the design rules for good ionic conductivity in an electrolyte solution or a molten salt? Are changes in behavior at particle-coated electrodes or highly porous electrodes associated just with an increase in surface area, or are quantum size effects encountered? And on and on. More than 50 panelists from the U.S., all experts in electrochemical science and technology, put their heads together to identify and recommend high-priority research directions that should be considered by the Basic Energy Sciences program. This was an exceptionally hard-working group; not only were the scientific issues discussed, but the workshop report was also nearly completely written and critiqued by the end of the fourth day. The report should be published by early summer, and hopefully it will exert some influence on funding for basic energy science. I am told that a symposium on the results from the EES workshop is being planned for the American Chemical Society national meeting this fall. Look it up if you want to learn more!
M A Y 1 , 2 0 0 7 / A N A LY T I C A L C H E M I S T R Y
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