If the Bugs Can Be Worked Out
IBM-led research to create lithium-air electric vehicle batteries gets a boost from Japanese chemical companies toward the goal of 800 kilometers out of a full charge.
Researchers predict a new type of lithium battery under development could give an electric car enough juice to travel a whopping 800 kilometers before it needs to be plugged in again—about 10 times the energy that today’s lithium ion batteries supply. It is a tantalizing prospect—a lighter, longer-lasting, air-breathing power source for the next generation of vehicles—if only someone could build a working model. Several roadblocks stand between these lithium–air batteries and the open road, however, primarily in finding electrodes and electrolytes that are stable enough for rechargeable battery chemistry.
IBM plans to take lithium–air batteries out of neutral by building a working prototype by the end of next year. The company announced Friday it has stepped up development efforts by adding two Japanese technology firms—chemical manufacturer Asahi Kasei Corp. and electrolyte maker Central Glass—to the IBM Battery 500 Project, a coalition IBM established in 2009 to accelerate the switch from gas to electric-powered vehicles among carmakers and their customers.
The lithium ion batteries used in today’s electric vehicles rely on a metal oxide or metal phosphate (typically cobalt, manganese or iron-based materials) cathode as a positive electrode, a carbon-based anode as a negative electrode and an electrolyte to conduct lithium ions from one electrode to the other. When the car is driven, the lithium ions flow from the anode to the cathode through the electrolyte and separator membrane. Charging the battery reverses the direction of ion flow.
Most fully charged lithium ion car batteries today will take an electric vehicle only 160 kilometers before petering out. (Nissan says its all-electric Leaf has a range of about 175 kilometers.) Plug-in electric vehicles such as the Chevy Volt have an even more limited range of up to 80 kilometers before its gas-powered motor must kick in.
The specifics of how lithium–air batteries will operate is still being determined, but the general principal is that, instead of using heavy metal oxides, oxygen would be collected from the air while an electric vehicle is in motion. The oxygen molecules react with lithium ions and electrons on the surface of a porous carbon cathode to form lithium peroxide. This lithium peroxide formation during discharge leads to an electrical current that powers the car’s motor. When charging, the reverse reaction takes place—the oxygen is released back to the atmosphere. The anode, meanwhile, is made of lithium, the lightest metal. Without the need for heavy metals the battery would be several times lighter while being able to store more energy than its lithium ion cousin.
via Scientific American – ᔥ
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