Yan Gao is a Senior Scientist in the Chemical and Structure Analysis Laboratory at GE-GRC in Niskayuna NY. Yan specializes in x-ray diffraction and synchrotron applications. A native of China, Yan earned a Ph.D. in chemistry from State University of New York at Buffalo (1990), and was a Beamline Scientist at the National Synchrotron Light Source before joining GE in 1994. Yan travels to various national laboratory facilities in order to perform novel experiments which cannot be performed in house at GE-GRC and for other functions such as proposal and facility reviews, user meetings, and workshops. Yan has been working with Global Research’s battery team for the past four years, primarily on synchrotron based structure analyses.
On June 13, 2011, the story of GE’s battery research using synchrotron radiation was posted at DOE’s website, titled “GE Uses DOE Advanced Light Sources to Develop Revolutionary Battery Technology ”. What you will read below is the story behind the story, more of a personal account, about our battery work at the National Synchrotron Light Source (NSLS). It’s about how we at GE Global Research work with national laboratories using their advanced characterization techniques to solve our important technological problems.
The NSLS is a user facility at Brookhaven National Laboratory, located almost in the geographic center of Long Island, about 50 miles east of New York City, and four-hour drive from GE Global Research in upstate New York. The NSLS, as the DOE article described, is a “football field-size” facility, which can be easily spotted from Google Map. It produces powerful x-rays called synchrotron radiation, which are several orders of magnitude more intense than laboratory x-rays and much more penetrating.
Synchrotron radiation was discovered at the GE Research Center in 1947, as mentioned by my colleague Ernie Hall in a previous posting. At present time, there are more than 60 synchrotron light sources worldwide used by researchers from universities, national labs, and industries. GE has been a synchrotron user since the 1980s, and has seen more applications in advanced materials characterization since 1995. Prior to the battery research, we worked at many beamlines at the NSLS on a wide range of materials, most notably on hydrogen storage materials funded by DOE, and have collaborated with many scientists at the facility. I spend a significant amount of time each year at the NSLS. So much so, that the lady at the Brookhaven housing office recognizes my voice when I call to make a reservation, which makes me feel special.
The challenge for in-situ x-ray measurements of the battery cell is its sheer size, 3.5 cm square in cross-section and 23 cm long, and its steel casing. Even synchrotron x-rays cannot penetrate through the cell unless they have very high energies. Beamline X17, which is equipped with superconducting wigglers, is the only beamline at the NSLS that provides such high-energy x-rays and has the potential to be used for in-situ work. There was another important attribute that made X17 unique: the strain-mapping facility located inside the B1 hutch, co-developed by Rutgers and the NSLS. This facility, taking advantage of the intense, high-energy, white beam from the superconducting wigglers, can define a small probing volume inside a bulk metal sample such as a turbine blade, and accurately measure the lattice strain distribution non-destructively.
While X17B1 is the most ideal choice for the battery measurement as we can see now, it was not obvious at beginning.Our initial test measurement was more curiosity than part of a grand plan. In one of my trips to Brookhaven, I told Zhong Zhong, a brilliant physicist at the NSLS and the beamline scientist at X17, about our battery work at the FRM-II , a neutron research facility in Munich Germany. He simply suggested that we could try it at the X17B1 beamline using the strain-mapping facility, because synchrotron has much higher flux than neutrons, and usually better spatial resolution. He could “squeeze” a few hours out of Rutgers beam time to test a GE cell. The key questions to answer were:if the x-ray beam could penetrate through the cell, if the measurement time would be fast enough for in-situ cycling, and if the data quality would be decent for phase analysis. Zhong thought we had a good chance to succeed; from our long history of working together, he was right most of the time.
The feasibility test took place in October 2007 and went very well. Soon after that, we went back to Brookhaven during our own beam time, equipped with furnace and battery cycler, to run the experiment at the operating temperature of 300°C and during charge or discharge cycles. Since then, my colleagues and I have taken a few trips each year to Brookhaven, having about four days of beam time each visit, working days and nights at the beamline X17B1. It was hard work but extremely rewarding, as we were capturing unseen phenomena as the cell was being cycled, which was not possible by other means; we learned new insights during each trip. Our work there helped our colleagues back home to better understand the chemistry inside the cell and optimize the chemistry and materials processing. As the synchrotron work went so well, we eventually stopped the neutron work at FRM-II after some preliminary measurements.
Of course, amid the hard work, we tried to have some pleasure as well, a balancing act between work and life, so to speak. One of the critical decisions to make each evening was where to have dinner, (yes, a decent meal was allowed even during the beamtime): steak, seafood, Chinese, or Japanese. No, we never went to McDonalds; that would have been bad for productivity and detrimental to enduring the long night hours ahead.
The battery team is a large multi-disciplinary team with mixed skill sets including chemistry, computational modeling, materials science, mechanical engineering, and so on. Many people have contributed to the synchrotron work at Brookhaven, either directly or indirectly, and they deserve special thanks for making this ongoing project successful. In addition to the indispensible role played by Zhong Zhong as mentioned before, Prof. Mark Croft of Rutgers helped us with data management. Inspired by the success on GE’s sodium metal chloride battery, Mark expanded the beamline to investigate other battery system such as Li-ion battery. Now Mark is leading an effort to propose a similar but more powerful high-energy beamline for NSLS-II , the new synchrotron source at Brookhaven (which was also mentioned in Ernie’s blog). My GE colleagues Job Rijssenbeek and Guillermo Zappi, a chemist and an electrochemist respectively, spent many sleepless nights at Brookhaven over the past few years. Their deep understandings of battery chemistry were essential to designing intelligent diffraction experiments. GE’s Energy Storage Platform Leader Glen Merfeld, who values highly our external collaborations with the national labs, has been a strong supporter of the Brookhaven work from beginning. It’s because of Glen and his counterpart at Brookhaven, Jim Misewich, this battery work got attention and progressed into DOE’s spotlight.
Reflecting on my experience of working at various national labs over the past many years, if there is something to be learned, it’s around communication. People working at national labs don’t quite know what problems the industrial folks are facing, and vice versa, the industrial people couldn’t keep up with the technical progresses made at the national labs. For example, even though the strain-mapping facility at the X17B1 had been around for many years, it had never been used for battery research till we connected the dots, at least to my knowledge. In O. Henry’s short story “ The Gifts of the Magi” , a young, money-stricken couple traded Christmas gifts with good intension but poor mutual understanding: the wife sold her beautiful long hair to buy a chain for her husband’s pocket watch, while the husband sold his pocket watch to buy a set of combs for his wife’s lovely long hair. I know this was not the point O. Henry wanted to make, but you know what I mean. Like the young couple in the story, industry and national labs may wish to stick (work) together, but they need to communicate better and understand each other, in order to form the “perfect union” and get the most out of the relationship.