Effect of Sulfur-Derived Solid Electrolyte Interphase on Li-mediated Nitrogen Reduction

The Li-mediated nitrogen reduction reaction (Li-NRR) has emerged as an environmentally friendly alternative for ammonia production. To improve Faradaic efficiency, energy efficiency, and process stability in the Li-NRR, it is essential to control the physicochemical structure of the solid-electrolyte interface (SEI), as the SEI determines the reactive ion transport and electrical conductivity. In this study, a sulfur-derived SEI is first introduced, aiming to enhance the stability and energy efficiency of Li-NRR. By incorporating dimethyl sulfide (DMS) into the base electrolyte, we engineered the SEI's physical structure from a film to a net-like structure. Introduction of Li2SO4 and Li2S to the SEI enhanced ion conductivity and electron insulation properties, leading to an improvement in the Li plating uniformity and a reduction in electrolyte decomposition. Whereas the cell potential increased more than 2-fold in the base electrolyte after 10 h, the introduction of sulfur maintains a steady cell potential even over 20 h, enhancing energy efficiency.