Parameters affecting ammonia production via lithium-mediated electrochemical dinitrogen reduction

NH₃ electrosynthesis is gaining interest as this molecule, essential for fertilizer production, may be exploited as a carbon-free fuel. However, NH₃ production relies almost exclusively on the Haber–Bosch process, which operates under extreme conditions, resulting in a global average ratio of about 2.5 tons of CO₂ emitted per ton of NH₃ produced.^[1] Moreover, the Haber–Bosch plants are usually centralized to maximize the efficiency. Many challenges slowed down the decarbonization of NH₃ synthesis.
A fully electrified N₂-to-NH₃ pathway is hindered by particularly low selectivity, leading to a limited production and Faradaic efficiency (FE). Recently, the lithium-mediated strategy in aprotic media has opened up to remarkable results, as it leverages the lithium singular ability to both activate N₂ and stabilize the intermediate, enabling simultaneous protonation at ambient conditions.^[2] After 300 h of continuous operation, an FE of 64% has been achieved.^[3] However, scalability and long-term stability remain unresolved, as a deep understanding of this dynamic system evolution.
The effect of different process parameters will be detailed, towards an efficient lithium electrodeposition, passing through the electrolyte engineering.^[4] In particular, the electrolyte composition and the electrochemical protocol were studied by means of different analytical and statistical tools. The main limitations encountered in studying this strategy will also be exposed. The findings underscore the potential of NH₃ electrosynthesis towards a more sustainable process, while identifying critical areas for future research.

References

[1] M. Wang, et al., Energy Environ. Sci. 2021, 14, 2535–2548.

[2] A. Mangini, et al., Adv. Energy Mater. 2024, 14 (25), 2400076.

[3] S. Li, et al., Nature 2024, 629.

[4] A. Mangini, et al., Angew. Chem. Int. Ed. 2025, 64 (8), e202416027.

This project has received funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (grant agreement No. 948769, project title: SuN₂rise).