Why the lithium air battery is over hyped

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IBM has made a lot of noise about its lithium air battery, which it says can hold as much energy in a given volume as gasoline can. But General Motors isn’t all that convinced that lithium air battery technology is worth the investment.

“From General Motors’ perspective, we are not investing in this technology because it’s not providing a substantial benefit,” said Thomas Greszler, manager of the cell design group at GM’s electrochemical energy research lab, during a presentation at battery symposium hosted by the Lawrence Berkeley National Laboratory on Tuesday. Essentially making the lithium air technology work will require some big improvements and the end results may not turn out to be worth the trouble and costs, says Greszler.

The goal

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Bold claims have been made for years about the blend of battery chemistry that can use air as the cathode. Back in 2009, IBM said lithium air batteries could hold at least 10 times more energy than the lithium-ion batteries on the market then. Earlier this year, IBM re-stated this dramatic improvement potential and dangled the vision of a battery system that one day can prolong the drive range of an electric car to 500 miles per charge, or about five times the range of existing electric cars.

Lithium-air batteries are attractive to researchers because they can rely on air as the cathode and lithium metal as the anode. Oxygen, being and abundant and doesn’t require heavy casing to contain it inside a battery cell, also theoretically can achieve a high energy density, which extends the driving range of an EV. In a typical battery cell, lithium ions travel from the cathode to the anode when you charge it (through the electrolyte), and the anode holds onto the lithium ions to store the energy. When you use a battery, the lithium ions move from the anode to the cathode and a resulting chemical reaction leads to the harvesting of the electrons.

However, many improvements will need to be made to make a lithium air battery a good fit for an electric cars. Greszler noted that the need to pump oxygen into the battery system means an air compressor and blower will need to be built into the car. Adding more parts is generally not a good approach when a major goal is to reduce the weight of the car to improve its performance and fuel economy.

Creating a watertight design is also critical because lithium metal is highly flammable and can ignite and burn when exposed to water. So removing water vapor from the air is a must.

As a result of some of these issues, a lithium air battery could be heavier than the advanced lithium-ion batteries under development now, and Greszler said it’s “highly unlikely that lithium-air will provide any cost savings.”

The hype

The promise of lithium air battery has also led to a level of hype, many researchers agree. One of the hypes is the belief that lithium air batteries could deliver about 1,300 watt hours per kilogram of energy, said Stan Whittingham, professor of chemistry and material science at the State University New York, in a talk that he titled, “Beyond Lithium Ion: A Reality Check.”

A more realistic estimate is the 800 watt hours per kilogram that startup PolyPlus is hoping to achieve. PolyPlus received a Department of Energy grant to work on encapsulating the lithium electrode to create a more stable battery system. In comparison, lithium-ion batteries used in cell phones today are in the 200 watt hours per kilogram range.

Whittingham said lithium air batteries might find good uses elsewhere, just not in cars. Whittingham also looked to “IBM is one of the culprits for hyping,” lithium air battery technology for electric cars.

Even if IBM delivers on this technology, everyone agrees that commercializing lithium air batteries will take a long time. IBM said its project won’t likely lead to a commercial product until 2020 or 2030.

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