Wednesday, November 9, 2016

Salty batteries

Salty batteries: Smartphones, laptops, electric cars--whatever the device, an efficient battery is high on any user's wish list. The search for the next-generation battery has recently focused on sodium- oxygen batteries. Theoretically, these should provide previously unattainable efficiency but their practical implementation has proven to be a stumbling block.

Researchers now report in the journal Angewandte Chemie, that a highly concentrated electrolyte solution may make the sodium-oxygen battery more stable, and therefore more practicable. Researchers have high hopes for alkali metal/oxygen batteries, because their theoretical energy density is particularly high. In such batteries, one electrode is made from the pure alkali metal. Upon discharging, this electrode gives up electrons to the circuit and positive ions to the electrolyte.

The counter electrode is made of porous carbon and is in contact with the air. At this electrode, oxygen is reduced by taking up electrons in the presence of the metal ions. This may result in a variety of metal oxide compounds. As the battery is charged, this process is reversed: Oxygen (O(2)) is released to the air at the positive electrode, while the alkali metal is deposited at the negative electrode.