Investigation of the solid electrolyte interphase (SEI) layer in the electrochemical Li-mediated ammonia synthesis

The Li-mediated ammonia synthesis (LiMeAS) is currently the only proven way to synthesize ammonia electrochemically. However, the exact mechanism is not fully understood, with recent publications stating that the elusive solid electrolyte interface (SEI) layer could be a very important factor. Similar to the battery literature, it is believed to prevent excess electrolyte decomposition and regulate the Li plating behavior. In the case of the LiMeAS the SEI layer may control the diffusion rate of the reactants, N2, H+ and Li+. In this proposal, we aim to fundamentally understand the SEI layer as well as the deposit of the electrode at different reaction conditions (electrolyte solvents, salts, current densities and pressures) and investigate how these changes influence the faradaic efficiency (FE). The expected results will help to further understand and improve the performance of the LiMeAs and bring us a step closer to a renewable ammonia production.

锂介导氨合成（Li-mediated ammonia synthesis, LiMeAS）是目前唯一经证实的电化学合成氨方法。然而，其确切机制尚未完全阐明——近期研究指出，难以捉摸的固体电解质界面（solid electrolyte interface, SEI）层可能是关键影响因素。与电池领域文献所述类似，该层被认为可抑制电解质过度分解并调控锂沉积行为。在锂介导氨合成体系中，SEI层或能控制反应物（N₂、H⁺及Li⁺）的扩散速率。本研究计划旨在从根本上解析不同反应条件（电解质溶剂、盐类、电流密度及压力）下SEI层的本质特征与电极沉积物特性，并探究这些变化对法拉第效率（faradaic efficiency, FE）的影响机制。预期成果将助力深化对锂介导氨合成过程的理解、提升其性能，并推动可再生氨生产技术的发展进程。