Unraveling Multiphase Conversion Pathways in Lithium–Sulfur Batteries through Cryo Transmission Electron Microscopy and Machine Learning-Assisted Operando Neutron Scattering
Jean‐Marc von Mentlen, Ayça Senol Güngör, Thomas Demuth, Jürgen Belz, Milivoj Plodinec, Pronoy Dutta, Alen Vižintin, Lionel Porcar, Kerstin Volz, Vanessa Wood, Christian Prehal
Abstract
High Resolution Image Download MS PowerPoint Slide Understanding the complex physicochemical processes in conversion-type batteries requires investigations across multiple length scales. Here, we present a methodological approach to examine Li–S batteries on the nanoscale by combining cryogenic transmission electron microscopy (cryoTEM) with operando small-angle neutron scattering (SANS). CryoTEM revealed discharge products with a biphasic structure consisting of nanocrystalline Li 2 S within an amorphous Li 2 S x matrix. Data analysis of complementary operando SANS measurements was accelerated by a convolutional neural network trained to predict scattering curves based on plurigaussian random fields, enabling comprehensive parameter space exploration for model fitting. Our findings are in line with disproportionation-driven deposition of Li 2 S 2 particles that agglomerate and partially reduce to Li 2 S via solid-state conversion. This challenges the conventional view of direct, stepwise electroreduction of polysulfides at the electrode–electrolyte interface. Overall, our multitechnique approach demonstrates the value of combining localized high-resolution imaging with time-resolved operando scattering measurements to understand complex electrochemical conversion pathways in next-generation energy storage systems.