Understanding Temperature and Pressure Effects of Lithium-Mediated Nitrogen Reduction

Abstract

Ammonia is a critical industrial commodity due to its importance for fertilizers, but the Haber-Bosch process for ammonia synthesis generates significant carbon emissions. A lithium-mediated electrochemical route towards ammonia synthesis has been developed and validated. Nitrogen transport through nonaqueous electrolytes and the resulting solid-electrolyte-interphase microstructure and chemistry are important factors in determining ammonia selectivity. Here, I describe efforts to understand the operating temperature and pressure effects on lithium-mediated nitrogen reduction. Pressure and temperature are tuning knobs that affect nitrogen transport, electrolyte properties, solid-electrolyte-interphase chemistry and lithium microstructure. By changing pressure or temperature, we can drive the system towards nitridation over parasitic hydrogen evolution. This helps to better understand various kinetic, thermodynamic and transport dependencies of the lithium-mediated nitrogen reduction reaction.