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lithium-air batteries

True or false: Lithium-air batteries will shortly revolutionize the electric and hybrid car industries.

The beliefs of naysayers to the contrary, some feel that lithium-air batteries have the potential to provide 20 times more power than the commonly used lithium-ion variety. That is, if they ever get them working.

How Does the Lithium-Air Battery Operate?

Lithium-air batteries utilize oxygen from the air around them to pull in electrons. The use of an external substance precludes the need to store all components inside, and that makes these batteries lighter and less complex. It may sound good, but it isn't all that easy.

The Trouble with External Air

In these batteries, while the anode contains lithium, the cathode contains ion-generating air. In order to produce ions inside the battery, the oxygen must get there in the first place. Once it's inside, something needs to prevent it from reacting negatively with the battery's internal components and causing premature failure.

At present, the problem is unresolved, and longevity is not this battery's greatest feature. Current prototypes can undergo only a limited number of charge/discharge cycles before they decay entirely.

The Peroxide Problem

In the current lithium-air battery, the recharging process results in the production of an oxygen radical that generates lithium peroxide. The reactivity leads to rapid decomposition of the battery's electrolytes.

Is the problem insurmountable? Researchers believe that it is not. The use of a non-reactive electrolyte, one that is impervious to the effects of oxygen, could solve it.

The recent discovery of an electrolyte-based substance that reacts well with oxygen promises to improve the stability of these batteries. If it does, they will potentially boast a capacity far greater than that currently offered by the lithium-ion variety.

Initial Research

Although the earliest research did uncover certain resistant materials, none would conduct a reliable charge in freezing temperatures. Then along came tetraethylene glycol dimethyl ether, a derivative of ethylene glycol. By combining it with a complex lithium salt known as LiCF3S03, researchers arrived at a conductor that worked well at low temperatures.

Better yet, because it reacted so quickly to oxygen, the intermediate radicals that would normally cause a problem had no time to form. Experimentation failed to produce signs of electrolyte decomposition.

This new prototype possessed an impressive stability. By the 100th charge cycle, the loss of power was barely perceptible, and its good performance continued across a variety of different charges.

A Good Start, But Only a Start

If that were the entire story, the problem might already be resolved. Unfortunately, although the conductor is a major portion of the battery's components, more remains to be tested.

However, if things go as hoped, the potential capacity of the lithium-air battery could far exceed that of the lithium-ion variety. Even with a doubling of the latter's capacity, that of the air variety would still outstrip it ten-fold.

The Future of Hybrid Vehicles

In the near future, Toyota and BMW will be joining forces to conduct further research into the lithium-air battery. Not only will the collaboration strengthen the bond between the two companies, but it will also speed development of an electric or hybrid car with the capacity of traveling as many as 500 miles before requiring a recharge.

In the hopes of the environmentally conscious, development of the lithium-air battery could sound the eventual death knell for gas-powered vehicles as we know them.