Reduction of N₂ to Ammonia by Phosphate Molten Salt and Li Electrode: Proof of Concept Using Quantum Mechanics

Electrochemical routes provide an attractive alternative to the Haber–Bosch process for cheaper and more efficient ammonia (NH₃) synthesis from N₂ while avoiding the onerous environmental impact of the Haber–Bosch process. We prototype a strategy based on a eutectic mixture of phosphate molten salt. Using quantum-mechanics (QM)-based reactive molecular dynamics, we demonstrate that lithium nitride (Li₃N) produced from the reduction of nitrogen gas (N₂) by a lithium electrode can react with the phosphate molten salt to form ammonia. We extract reaction kinetics of the various steps from QM to identify conditions with favorable reaction rates for N₂ reduction by a porous lithium electrode to form Li₃N followed by protonation from phosphate molten salt (Li₂HPO₄–LiH₂PO₄ mixture) to selectively form NH₃.