Pumping up rechargeables

Rechargeable lithium batteries haven't really lived up to their expectations. They run down when they're not being used, get old and stop taking charge, and freeze if they get too cold.

INEEL chemists have given lithium rechargeables a new heart - a solid centre with unique properties that lets the batteries operate even in really cold temperatures. The new batteries also have a much longer shelf-life and are safer than conventional batteries.

The solid centre of the new battery is a mix of a gel-like polymer and a powdery ceramic that forms a clear membrane. When sandwiched between two electrodes, the membrane acts as an electrolyte.

The membrane replaces liquid and gel electrolytes in conventional rechargeable lithium batteries. Unlike liquid and gel electrolytes, the solid membrane doesn't leak in the battery and doesn't form insulating deposits that eventually cause battery death.

The solid electrolyte - essentially a plastic - is also a lot safer than conventional electrolytes. The liquid electrolytes in currently available lithium batteries are usually flammable, and the reason they can explode upon recharging.

Most exciting is the potential for batteries made with the INEELelectrolyte to travel the cold reaches of space. The membrane doesn't melt at high temperatures that degrade conventional electrolytes and continues to function at about 100 degrees Farhenheit below zero, unlike liquid and gel electrolytes that freeze.