Molten Electrolyte-Air Battery Debuts

One factor impeding wide use of electric vehicles is their limited driving range per charge compared with the driving range per fill-up of petroleum-fueled vehicles. New types of batteries with exceptionally high charge capacities could give electric cars a needed boost. George Washington University chemists now report that a new class of battery that draws oxygen from the air and features a molten electrolyte may do the trick (Energy Environ. Sci. 2013, DOI: 10.1039/c3ee42654h). Stuart Licht, Baochen Cui, and coworkers studied three types of rechargeable molten electrolyte-air batteries with theoretical charge capacities that are roughly 1.5 to 4.5 times as high as the capacity of prototype lithium-air batteries, which far outstrip commercial lithium-ion batteries. One of the group’s high-capacity batteries uses a molten carbonate electrolyte and draws oxygen from the air to convert iron to iron oxide. Recharging the battery reverses the reaction. The team also demonstrated high capacities in batteries based on two other reversible reactions: converting elemental carbon to CO₃^2– and VB₂ to B₂O₃ and V₂O₅. A range of parameters needs to be explored to optimize the battery cycling characteristics, the researchers say.