Upshifting\nLithium Plating Potential To Enhance Electrochemical\nLithium Mediated Ammonia Synthesis

The\nelectrochemical lithium-mediated N<sub>2</sub> reduction is\na promising process for sustainable ammonia synthesis. Unfortunately,\nfundamental understanding linking the interfacial chemistry of lithium\nplating with ammonia efficiency is not well understood. We investigated\na series of tetrahydrofuran electrolytes (LiClO<sub>4</sub>, LiBF<sub>4</sub>, LiTFSI, LiFSI) at 0.2–7.0 M. The Li<sup>+</sup>/Li\npotential (<i>E</i><sub>Li+/Li</sub>) measured against the\nelectrolyte-invariant Me<sub>10</sub>Fc reference increased with more\ndissociative salts and higher concentration. The upshift in <i>E</i><sub>Li+/Li</sub> was found to correlate with greater ammonia\nproduction stability and faradaic efficiency as well as the production\nrate. This correlation could be attributed to altered solid–electrolyte\ninterphase (SEI), which revealed prominent anion-derived (LiF) and\nalkoxide (LiOEt) species with increasing <i>E</i><sub>Li+/Li</sub> from Raman spectroscopy, potentially providing more Li<sub><i>x</i></sub>N and enhanced ion transport. Such insights can be\nused to guide the design of electrolytes to promote lithium-mediated\nammonia synthesis for practical applications.