SLAC postdoc Johanna Nelson used X-ray diffraction and transmission X-ray microscopy to capture nanoscale images of the battery’s components, a lithium anode and a sulfur-carbon cathode surrounded by an electrolyte. They captured images of sulfur particles before, during and after battery discharge, and found some unexpected results.
Previous research on these types of batteries showed the sulfur and lithium form certain compounds when they react, trapping the sulfur permanently in new compounds. Formation of these compounds, called polysulfides, can kill a battery in just 10 charge-discharge cycles — not nearly good enough for almost any tech, let alone something like an electric car. But this new research shows it may not be as bad as expected. Very few of these polysulfides actually went into the electrolyte, far less than other research had shown. This means it might not be too difficult to trap them at the cathode, preventing any from leaking into the electrolyte and harming the battery.