Inorganic ionic liquids can be used as electrolytes in fuel cells, according to researchers from the US. 

Austen Angell and colleagues at Arizona State University show that inorganic ammonium salt mixtures can actually be used in place of the commonly used organic ionic liquids as fuel cell electrolytes. The fuel cell electrodes can operate in the same temperature range as existing fuel cells, while the efficiencies at low current densities can be much better. 

There has been much attention focused on the development of ionic liquid electrolytes for fuel cells using large organic cations. These liquids are made by transferring protons from acid molecules to organic amine bases. Simple mixtures of inorganic cation salts have been previously overlooked, despite the fact they are liquid at low temperatures too and highly conducting. Another advantage is that these electrolytes can be neutral, which opens the door to alternative catalysts for the fuel cells, such as enzymes. 

According to Angell, the future challenges in this area will be getting the devices to work at even higher currents and lower temperatures. 

Katherine Vickers