Image courtesy of GE
GE's new "Durathon™" sodium metal halide battery.
The story of American manufacturing over the past two decades has too often been a tale of outsourcing, off-shoring, and downsizing—not least in Upstate New York, which has probably seen more than its fair share of factory shutdowns and job losses in recent years. Today, however, General Electric is bucking the trend, putting the finishing touches on a new manufacturing facility in Schenectady. The plant, which will begin operations toward the end of the year, is eventually expected to create more than 300 jobs. It will produce a new advanced line of heavy duty batteries, which GE plans to sell to telecoms, utilities, data centers, and other industrial and transportation customers worldwide.
The new batteries, based on sodium metal halide technology, boast three times the energy density and charging power of the lead-acid batteries they are designed to replace, according to the company. GE engineers also say the batteries have long cycle life, withstanding thousands upon thousands of charge and discharge cycles, for expected lifetimes of up to twenty years, and can operate in a wide range of temperature environments.
To help achieve these breakthroughs, GE researchers relied on two of the Nation's most advanced and sophisticated scientific user facilities, the National Synchrotron Light Source (NSLS) at the U.S. Department of Energy's (DOE) Brookhaven National Laboratory on Long Island and the Advanced Photon Source (APS) at DOE's Argonne National Laboratory outside Chicago. NSLS enabled GE researchers to understand in detail the internal chemistry of an actual commercial battery while charging and discharging in real time. Additional studies of battery cross-sections at APS helped engineers further understand the system.
The data gathered from the two light sources helped GE's engineers to fine-tune battery design to maximize performance and improve reliability, creating what they say will be a world-leading technology.
The evolution of GE's new line of batteries—christened "Durathon™" by the company—is a paradigmatic tale of how science can foster innovation and innovation can generate jobs.
GE had been a user of NSLS since its commissioning in the mid-1980s. NSLS is one of five major advanced light sources supported by DOE's Office of Science at national laboratories around the Nation. These are large, typically football field-sized installations with one major purpose: to generate extremely powerful and highly focused beams of x-rays.
Image courtesy of GE
In-situ X-ray diffraction setup (NSLS Beamline X17B).
Even since their discovery by Wilhelm Roentgen in 1895, x-rays have proved to be one of science's most powerful tools for probing the secrets of matter, both organic and inorganic. From dental x-rays to CAT scans, they are the indispensable diagnostic tools of medicine. They are the workhorse tools of airport and public building security. They are as familiar a fixture of modern life as the elevator or the internal combustion engine.
But x-rays from light sources such as NSLS sources are special. They are finely focused and exquisitely tunable to interact with matter in very specific ways. Using them, scientists can discover precise properties of matter with resolution down to the molecular and atomic scales.
GE's initial interest in the sodium metal halide technology was rooted in its plans to develop a hybrid locomotive (GE is a major producer and supplier of diesel locomotives worldwide). Over time GE recognized the potential for a broader energy storage business based on the new technology. But before the product would be ready for prime time, it would have to be substantially improved.
Our collaborations with the National Synchrotron Light Source and the Advanced Photon Source have helped to improve our fundamental knowledge and in turn have allowed us to realize significant gains in battery performance. These advancements are foundational to our new business and our ability to bring leadership technology to market.” Glen Merfeld
GE, Energy Storage Platform Leader
The basic chemical reaction at the heart of a sodium metal halide battery is comparatively simple: during charging, sodium chloride (salt) reacts with metal through a series of intermediate steps to produce, as a final product, sodium plus a metal chloride compound. During discharge the reaction is reversed.
One drawback is that the reaction must take place at very high temperatures, between 250°C and 350°C, temperatures at which the electrolyte is actually a liquid. GE engineers would ultimately turn this drawback into an advantage. In the meantime, the sodium metal halide technology offered several important benefits: very high energy density (that is, the amount of energy that can be stored per weight or volume of the battery); long lifetimes under repeated charge-discharge cycles; tolerance to overcharging and undercharging; resilience to multiple cell failures; readily available components with relatively low environmental impact; and comparative safety in the event the battery would be physically damaged.
To better understand the sodium metal halide chemistry, GE made use of a beam line at NSLS developed by Rutgers University that delivers high energy x-rays capable of penetrating an object and gaining information about the chemical content of its interior. Rutgers had developed this particular capability for "in situ," or real time, studies of materials under stress. Chi-Chang Kao—then Director of NSLS and now Director of another DOE light source at SLAC National Accelerator Laboratory in California—encouraged GE researchers and pointed them to the Rutgers beam line with its special in situ capabilities.
Using the Rutgers set-up, the GE-led research team was able to take an actual commercial battery cell, measuring 23 centimeters high by 3.5 centimeters square, encased in a metal housing, and surrounded by a heater (to keep the battery cell at the operating temperature). In this state, researchers were able to run the battery cell through actual charge and discharge cycles while observing its internal workings with the x-ray beam.
The technique used for these studies, called "energy dispersive x-ray diffraction," provides a wealth of information. Through x-ray diffraction patterns, the technique enables researchers to identify not only the chemicals but also the relative quantity and location of the chemicals within the object under study. Using this in situ set-up, GE researchers were able to observe in very fine detail the chemical reactions occurring within the battery in real time—to trace every step of the reactions as they occurred. The x-rays also permitted measurements of physical density. The set-up gave researchers the capability of "4-dimensional" observation. They could scan the battery cell physically with the x-ray beam or hold the beam in one location as they ran the battery through charge and discharge cycles over time.
Photo courtesy of Brookhaven National Laboratory
National Synchrotron Light Source at Brookhaven National Laboratory.
Based on the research at NSLS, GE engineers were able to verify the presence of an intermediate reaction as well as to make several other improvements to the battery's performance and reliability through tweaks to the battery's chemistry.
Additional studies of battery cross-sections at Argonne National Laboratory's synchrotron light source, the Advanced Photon Source, helped GE engineers further understand battery reaction processes.
The light source work supplemented GE internal studies of the batteries using computerized axial tomography (CAT) technology (which GE owns and markets through its Measurements and Control Solutions business) and a range of other instrumentation, along with extensive computer modeling and simulation, primarily at GE Global Research in Niskayuna, New York. At the same time, GE engineers developed an insulated housing for the battery to maintain it at the proper temperature, permitting the final battery product to operate self-contained and safely in an extraordinarily wide range of ambient temperature environments.
As it pursued product development, GE partnered with the State of New York and the federal government, garnering $15 million in state tax breaks and $25.5 million in tax credits under the American Recovery and Reinvestment Act to help finance construction of the Schenectady factory.
Whether GE's new product line will succeed remains to be seen, but the story of the Durathon™ battery illustrates perhaps more vividly than most how the ability to innovate, create jobs, and lead in technology markets can be very closely tied to a nation's basic scientific capabilities and facilities. The story also helps explain why competition among nations to develop new, more capable advanced light source facilities such as NSLS and APS is so intense today. The work at DOE-supported light sources proved critical in enabling GE engineers to produce not just a solid, but a world-leading product—with sufficient technological margin of advantage to justify manufacturing it in the United States rather than with cheaper labor abroad.
Meanwhile, GE is so persuaded of the value of light sources that it has a joint proposal with Rutgers and others for the creation of a new beam line at NSLS-II, the far more powerful follow-on light source to NSLS, currently under construction at Brookhaven. In the words of GE's Glen Merfeld, Energy Storage Platform Leader, "Our collaborations with the National Synchrotron Light Source and the Advanced Photon Source have helped to improve our fundamental knowledge and in turn have allowed us to realize significant gains in battery performance. These advancements are foundational to our new business and our ability to bring leadership technology to market."
—Patrick Glynn, DOE Office of Science, Patrick.Glynn@science.doe.gov
Scientific User Facilities (National Synchrotron Light Source and Advanced Photon Source): DOE Office of Science
J. Rijssenbeek et al. "In situ X-ray diffraction of prototype sodium metal halide cells: time and space electrochemical profiling," Journal of Power Sources 196 2332 (2011).
GE Energy Storage Home (http://www.geenergystorage.com/)
National Synchrotron Light Source (http://www.nsls.bnl.gov/)
Advanced Photon Source (http://www.aps.anl.gov/)