Ammonia (NH3) is one of the most widely produced chemicals worldwide with a key role in the growth of global economy. Traditional ammonia synthesis by the Haber-Bosch process runs at high temperature and pressure with low hydrogen conversion

high energy consumption and severe environmental pollution. Electrochemical synthesis of ammonia has been immensely studied as it is operated at ambient temperature and pressure. The electrochemical synthesis has been improved via choosing electrolyte systems

preparing electrodes and electrocatalysts

and constructing highly efficient and stable electrochemical cells. This review summarized recent progress of electrochemical ammonia synthesis in five electrolyte systems including liquid electrolyte

proton conductor ceramic membrane

molten salts

a composite electrolyte of molten salts and ceramic membrane

and organic proton exchange membrane. Mechanism of electrochemical ammonia production

current technical status

major challenges and future directions were discussed.