Variations and applications of the oxygen reduction reaction in ionic liquids.

Increasing energy demands call for new energy storage technologies with high energy density to meet current and future needs. Metal-air batteries are especially attractive due to their superior specific energy, which is as much as 8 times that of today's best Li-ion batteries. However, the practical values achieved to date are far from the theoretical one and require further research to enhance the battery performance. The electrolyte plays an important role in the performance of the battery whose properties can be tuned by varying the chemical composition and through the use of additives. That is the case of ionic liquids which offer a wide variety of anion-cation combinations to realise maximum performance. This feature article overviews recent developments in ionic liquids as electrolytes for both magnesium-air and sodium-air batteries.