Jongwoo and his team from Seoul are “friendly users”. This name is given to scientists who do their experiments on a pristine machine, before it goes into user operation. Back in Korea we called them to hear more about their special beamtime and what it means for their battery research.
Who are you and how did you discover BESSY II?
I am Jongwoo Lim, assistant professor at the department of chemistry at Seoul National University. My research group “Battery and Energy Research Lab” counts many talented young scientists. In 2018 a colleague from the Max Planck Society invited me to give a talk and, on this occasion, I visited BESSY II. Back in Seoul I wanted my team to discover this amazing science environment.
Getting beamtime at BESSY II, how does this work?
The competition for beamtime is very strong, many scientists want to come to BESSY II! We send in a proposal and were rejected several times. Finally, after 2 years we got the green light for some beamtime at MAXYMUS, the beamline of the Max Planck Institute for Intelligent Systems (more below). And on top of that, beamline scientist Markus asked us if we were interested to use and test MYSTIIC (Microscope for x-raY Scanning Transmission In-situ Imaging of Catalysts). This new microscope will go into operation in Spring 2022.
How was your beamtime at BESSY II?
It was wonderful, we got two weeks of consecutive beamtime at BESSY, back-to-back doing research at both beamlines MAXYMUS and MYSTIIC. Although I came only a few days, my 4 PhD students stayed the entire time (~20 days). In the first week the shifts were 12 hours and in the second week we had 3 days off before starting 4 days consecutive beamtime (60 hours)!
For us, the biggest challenge was how to be able to eat with consecutive night shifts as you are not allowed to eat inside BESSY – luckily there was a personal refrigerator compartment for our team in the coffee area! And of course, the next supermarket is not far away.
What were your experiments all about?
Our goal was to visualise lithium movement within the individual lithium-ion battery particles while we cycle the customised micro-batteries. There are millions/billions of battery particle in lithium-ion batteries in our cell phones. The lithium movement within the battery particles fundamentally determines the battery cell performance. Yet, such lithium movements are not well understood. Both MAXYMUS and MYSTIIC are state-of-art x-ray microscopes which accurately and reliably visualise lithium within battery particles at tens of nanometer resolution. We have some expertise to cycle the individual battery particles inside the vacuum chamber of these X-ray microscopes. Fortunately, everyone at BESSY and our team made a great harmony, which allows us to take a video of lithium movement. We found interesting phenomena. Yes, I can say that the experiments went very well this time.
How was it to work with people on site at BESSY II?
Due to the pandemic, we were not able to meet many people, however we felt very welcome. Markus and his colleagues Sebastian and Thomas were extremely helpful and supportive when it came to use the microscope MYSTIIC at EMIL (Energy Materials in situ Lab).
Additionally, we were very impressed that we were able to use all the equipment at EMIL. They have a chemical lab nearby, we had all we needed just around the corner: hot plates, glove boxes… it was perfect preparing our samples there. We liked this scientific environment!
What do you think about MYSTIIC?
It is an amazing tool for us and our battery research. MYSTIIC is a newly built scanning transmission x-ray microscope (STXM) and ready for many crazy experiments like what we doing. For our experiments, there are so many factors which can go unexpectedly wrong. For instance, loading and managing liquid-flowing micro-batteries inside the vacuum chamber is not too easy. The soft x-ray optics in STXM are very delicate and located extremely close to the sample. Thus, we had to carry our every step of experiment procedure very carefully and slowly. We always run out of time and beamtime is very precious.
MYSTIIC made our beamtime efficient. The BESSY team developed a new software based on Python for MYSTIIC, it works very fast and is user friendly. They also built a specific camera, which enables you to see through the vacuum chamber, this is terrific.
MYSTIIC took videos of lithium movement within the lithium-ion battery particles. It is really impressive to be able to see into the inside the battery materials.
How was it preparing your trip to Germany?
When we got the message accepting our proposal, we knew what to do: getting vaccinated to be able to travel and to work at BESSY II. When this was done, we had more of an administrative challenge! We planned to take a very expensive piece of equipment with us for the in-situ experiment whose design is legally protected. Hummingbird scientific (HB), the manufacturer of our in-situ tool, and HZB had to agree on non-disclosure. Thanks to various people at HZB and HB who were understanding and committed to make it possible for us to come, it worked well, and all the paperwork was signed in due course.
What was the most exciting part of your stay at BESSY II?
With the type of experiment we do, all can be destroyed in a couple seconds. The chamber where the sample lays is under vacuum. Sometimes very thin silicon nitride membrane which encapsulates the liquid electrolyte of micro-batteries can break. Unfortunately, this happened badly and damaged the x-ray optics in vacuum chamber. We are so thankful for Markus’ help. He fixed it straight away, this was greatly appreciated. Sometimes you need to stop your experiment for many days when this kind of thing happens.
And now, what are you going to do?
We came with two projects for which we did and will do measurements in different facilities: BESSY II but also the Canadian Light Source, Advanced Light Source in Berkeley and Pohang Light Source in Korea. We bring all the data together, it is very collaborative and with all the videos we can take, we will see a scientific story appear.
Also, I know that we will be back at BESSY II in April 2022 to work again with MYSTIIC. We cannot wait as we really enjoyed our time here in Berlin.
Thank you ever so much for this interview, dear Jongwoo Lim and team! Looking forward to welcome you soon again at BESSY II in Berlin.
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