Intercoupled electrocatalytic ammonia synthesis via a looped Li–N2/H2 battery

ABSTRACT Electrochemical ammonia (NH3) synthesis offers a sustainable pathway for the chemical industry. However, the fundamental proton-coupled nitrogen (N2) reduction process has led to the competing H2 evolution and low energy efficiency, particularly at high current densities. Herein, we present the design of a looped Li–N2/H2 battery that decouples N2 reduction from protonation by two separate sub-reactions of electrocatalytic N2 reduction in discharging (6Li+ + 6e− + N2 → 2Li3N) and electrocatalytic H2 oxidation in charging (H2 → 2H+ + 2e−), which are intercoupled into a synthetic loop to enable NH3 synthesis (Li3N + 3H+ → NH3 + 3Li+) without H2 evolution. This approach achieves record-high energy efficiency (26.0% ± 0.9%), Faradaic efficiency (63.7% ± 2.3%), and high NH3 production rate (1 mA cm−2, 0.12 mol h−1 m−2) under mild conditions. These results significantly lower the cost of ammonia production compared to conventional electrochemical methods, highlighting its promising potential for practical applications.