Gallium Cathode Redirected 96% of Current Into Ammonia

Researchers at Monash University and RMIT University have changed the cathode chemistry used in one leading route to electrically produced ammonia. Their peer-reviewed study, published in Cell Press Blue on 8 October, replaces the usual deposition of lithium metal with a gallium-based material that alloys with lithium.

That distinction matters because nitrogen molecules are exceptionally stable. Lithium can help activate them, but depositing lithium metal requires a strongly negative electrical potential. Part of the supplied energy is therefore spent reaching the chemical conditions needed before useful ammonia formation can occur.

A different role for lithium

The new cathode accepts lithium into an alloy. According to the researchers, this lets the lithium-mediated nitrogen-reduction reaction operate at a substantially more favourable potential while preserving the chemistry needed to convert nitrogen into ammonia.

The result is not a lithium-free process. It changes where lithium sits and how much electrical driving force the cathode needs.

Under optimised laboratory conditions, the team reported a faradaic efficiency of 96 ± 6%. Faradaic efficiency measures how much electric charge reaches the intended product rather than side reactions. The group also calculated that the design could support an energy efficiency of at least 22%. Monash described the work as overcoming a fundamental limit of the conventional lithium-deposition approach in its research announcement.

Those two percentages answer different questions. The first concerns the share of current producing ammonia. The second estimates the useful chemical energy in the ammonia relative to the electrical energy supplied. High selectivity alone does not guarantee an economical industrial process.

Why ammonia production is difficult to decentralise

Most ammonia is made in large plants because conventional production favours centralised equipment and steady operation. An electrochemical route powered by renewable electricity could eventually allow smaller facilities to produce fertiliser feedstock nearer to farms or stranded renewable resources. That prospect is one reason the research is being developed with Monash spin-out Jupiter Ionics, as also reported by Phys.org.

The advance therefore widens the design space for lithium-mediated ammonia synthesis rather than completing the route to green fertiliser. Its value will depend on whether the favourable cathode potential survives larger cells, continuous operation and the balance-of-plant losses that laboratory measurements do not capture.