Probing Li ₂ S Activation Mechanism in Lithium–Sulfur Batteries via Multimodal Operando Techniques

High Resolution Image Download MS PowerPoint Slide High kinetic barrier of Li 2 S demands high charging potentials to get activated, causing electrolyte decomposition and active material loss. A clear understanding of the reaction mechanism is required to mitigate this issue. This study reveals the major cause of the activation barrier: prior dissipation of polysulfides (PS) to the anode, which suppresses essential chemical oxidation pathways essential for Li 2 S oxidation. Isothermal microcalorimetry (IMC) and operando electrochemical impedance spectroscopy (EIS) provided further insights into role of chemical reactions and PS dynamics. The mechanism by which subsequent cycles overcome the activation barrier is also explored. To verify this understanding, a novel strategy is proposed to suppress dissipation and promote a radical-mediated conversion mechanism, thereby increasing the generation. This is achieved using a gel polymer electrolyte (GPE) and a high donor number (HDN) solvent. Both GPE and HDN solvents significantly enhance the kinetics during charging, effectively reducing the activation barrier.