Real-Time Imaging of Lithium-Sulfur Batteries
Researchers at Stanford University and the SLAC National Accelerator Laboratory are using X-ray technology to observe lithium-sulfur batteries and their findings could lead to improvements in this promising power source for electric vehicles. Postdoctoral scholar Johanna Nelson demonstrates the transmission X-ray microscope at SLAC's Stanford Synchrotron Radiation Lightsource, a powerful device that takes nano-scale images of chemical reactions in batteries while they are running.
Transcript
00:00:00 [sound] Stanford University. Lithium sulfur batteries have a very high capacity. However, their cycle life is very short so you, you want a battery that can be cycled multiple times. So you don't want to lose your active sulfur material so that it can't be reused in the next cycle. Using scanning electron microscopes, previous studies have showed that the sulfur particles that start out before you start cycling this battery are completely gone by the end of, of the discharge cycle. But electrons do not penetrate into materials very well, so you could never look at a full battery in an electron microscope, so we have
00:00:46 to use x-rays. This is an x-ray microscope. X-rays come from here into the first lens which is an objective lens. And the objective lens creates an image which is going to be recorded on our camera or our CCD detector which is far down there. We were looking at a battery which we put here and we attached electrode leads off of the battery so that we could cycle the battery while we were imaging. So, we take images every five minutes and cycle the battery for its discharge and then charge state. So you can speed up that and, and get a video of what's happening. In this example in a battery, so what would happen in over eight hours, we can make a video in a matter of a minute. What we found, looking at the battery while it's operating and not having to disassemble it using x-rays
00:01:40 we found that the sulfur particles did not dissolve. That the particles for the most part stayed where they where for lithium sulfur batteries the significance is that many scientists and engineers are working on developing ways of trapping the sulfur In to stay on the electrode. And so this technique can be used by them to test whether or not their trapping is sufficient enough. You need a synchrotron to do this very quick imaging in most laboratories. A single image would take ten minutes for us. A single image takes half a second. For more, please visit us at stanford.edu.