Long-term continuous ammonia electrosynthesis.

Ammonia is crucial in fertilizer and chemical industries and is seen as a carbon-free fuel 1 . The ammonia electrosynthesis from nitrogen at ambient conditions offers an attractive alternative to the Haber-Bosch process 2,3 . The lithium-mediated nitrogen reduction (Li-NRR) represents a promising approach for continuous-flow ammonia electrosynthesis, coupling nitrogen reduction with hydrogen oxidation 4 . However, tetrahydrofuran (THF), commonly used as a solvent, impedes long-term ammonia production due to polymerization and volatility issues. Here we show that a chain ether-based electrolyte enables long-term continuous ammonia synthesis. We find that a chain ether-based solvent exhibits non-polymerization properties, a high boiling point (162 °C), and forms a compact solid-electrolyte interphase (SEI) layer on the gas diffusion electrode (GDE), facilitating ammonia release in the gas phase and ensuring electrolyte stability. We demonstrate 300 h continuous operation in a flow electrolyzer with 25 cm 2 electrode at 1 bar and room temperature, and achieve a current-to-ammonia efficiency of 64 ± 1% with unprecedented gas phase ammonia content of ~ 98%. Our work highlights the crucial role of the solvent in long-term continuous ammonia synthesis.