Crystal structure of submicron-sized sulfur particles using 3D ED obtained in atmospheric conditions.

Lithium-sulfur batteries are a promising candidate for the next generation of rechargeable batteries. Despite extensive research on this system over the last decade, a complete understanding of the phase transformations has remained elusive. Conventional in-situ powder X-ray diffraction has struggled to determine the unit cell and space group of the polysulfides formed during charge and discharge cycles due to the high solubility of these solid products in the liquid electrolyte. With the improvement in in-situ electrochemical set-ups dedicated to transmission electron microscopes, three-dimensional electron diffraction (3D ED) has the potential to capture the crystal structures of the polysulfides during cycling. In this work, the structure solution and refinement from 3D ED data of elemental sulfur, known to sublimate in the vacuum of transmission electron microscopes, is enabled through the use of an environmental cell with a micro-electromechanical system. This work represents the first step in characterizing sulfur's transformation into lithium polysulfides using in-situ 3D ED.