One of the main areas researchers are exploring for clues to that breakthrough is metal-air batteries, especially ones based on lithium. Metal-air batteries get their name from reactants that provide energy by undergoing electrochemical reactions. In zinc-air cells, for example, energy is released by oxidizing zinc (which is held within the battery case) with oxygen from the air. Insofar as the oxidizer is not stored in the battery but supplied continuously from an external source—air—these kinds of batteries are similar to fuel cells, in which neither the oxidizer nor the fuel is packaged inside the cell. The metal-air battery concept isn’t new. Nonrechargeable Zn-air button-cell hearing-aid batteries can be found in drugstores everywhere. In contrast, rechargeable metal-air batteries, and in particular Li-air batteries, remain in the research phase but continue to attract new investigators because of the promise these batteries hold. “Lithium-air is a battery technology that’s extremely high risk, but one that’s also potentially extremely high gain,” asserts Hubert A.
by Mitch Jacoby |
November 22, 2010