Weakened ionization electrolyte with n-hexane additive enabling high activity of lithium-mediated nitrogen fixation

Abstract

Lithium-mediated nitrogen reduction reaction (LMNRR) is a promising route for sustainable ammonia synthesis, but the generation of excessive solid electrolyte interphase (SEI) severely limits its efficiency. Here, we tackle this challenge by introducing n-hexane as an electrolyte additive to weaken LiClO₄ ionization, achieving minimized dissociation via squeezed solvation shells with compact ion pairs. Molecular dynamics simulations and experimental characterizations reveal that n-hexane enriches anion coordination around Li⁺, endowing the electrolyte with robust anti-reduction capability. This suppresses SEI overgrowth, reduces interfacial resistance, and accelerates N₂ diffusion. Consequently, a thinner, inorganic-rich SEI is formed, enabling high nitrogen flux and rapid active Li₃N generation kinetics. Consequently, the proof-of-concept system achieves unprecedentedly high Faradaic efficiency of 53.8 %±8.2 % at 10 mA cm⁻² and NH₃ yield rate of 88.57±9.5 nmol s⁻¹ cm⁻² under ambient conditions, making a giant step further toward industrializing the electrochemical ammonia production.