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Image Credit: Jurvetson on Flickr

Published on April 24th, 2012 | by Nicholas Brown

8

Air-Breathing Batteries: How Does Recharging Your Electric Car Only Monthly Sound?



Tesla Roadster – Deskinned

IBM-led researchers have estimated that a recent battery technology under development could enable electric vehicles to travel 800 km (497 miles) per charge. This technology is a lithium-ion battery that utilizes air (partially) to generate electricity.

The lithium-air battery was invented years ago, and researchers have been working on improving it since then, primarily due to the fact that it has a potential energy density of 5,000 Wh/kg (5 kWh/kg), meaning that it has the potential to store extremely large amounts of energy in a lightweight package. (Wh = Watt-hours of energy storage capacity… in this case).

Take this example: 24 kWh is an average size for an electric vehicle battery pack. A 24-kWh lithium-air battery pack could theoretically weigh as little as 4.8 kg, or 10.5 pounds, which is less than some large bags of rice.

How Lithium-Air Batteries Compare to Typical Batteries in Use Today

  • Typical lithium-ion (li-ion) batteries have energy densities ranging from 95 to over 200 Wh/kg.
  • Lead acid-battery energy density ranges from 30-40 Wh/kg (rarely used for commercial electric vehicles — they are popular for DIY EVs, though).
  • Nickel-Metal Hydride (NiMH) battery energy density ranges from 60-120 Wh/kg. This type of battery is used in older EVs (and recent model Prius vehicles).

How This Benefits Electric Vehicles

  1. Since a higher-energy-density battery is lighter, it weighs down electric vehicles less, translating into greater performance — greater efficiency and/or a longer driving range.
  2. Cheaper electric vehicles (if the battery does not cost more than traditional ones) is also a possibility. When the energy density of batteries improves, fewer batteries can be used to achieve the same driving range and performance, and this has the potential to cut the cost of  electric vehicles. Batteries can account for 40% of the cost of an electric vehicle. Lithium-air batteries’ potential to lower the weight and battery capacity requirements of vehicles is so great that even at a much higher price than typical batteries, they could lower the overall cost of an electric vehicle.

Conclusion

Lithium air batteries are still under development, but IBM, which announced plans to research and develop lithium-air technology about a year ago, says that it hopes to have a working prototype available by the end of the year.

h/t Scientific American
Photo Credit: jurvetson

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About the Author

writes on CleanTechnica, Gas2, Kleef&Co, and Green Building Elements. He has a keen interest in physics-intensive topics such as electricity generation, refrigeration and air conditioning technology, energy storage, and geography. His website is: Kompulsa.com.



  • Thomas Cheney

    How much heavier would the battery be after it is discharged in comparison to a charged state?

    • You are an idiot

      ……Yeah electricity weighs SOOOO much.

      • Ross

        That question isn’t completely silly as it is a “Lithium-Air” battery. Not a closed system!

  • Captivation

    “A 24-kWh lithium-air battery pack could theoretically weigh as little as 4.8 kg, or 10.5 pounds, which is less than some large bags of rice.”

    And uncooked rice offers 1600 calories per pound = 1.86 watt/hours/pound. That 10.5 bag of rice only offers about 20 watt hours of power while the same weight lithium air battery offers 24000 watt hours.
    Last night I ate Chinese food (vegetarian combo #4) which has even less energy. (Cooked rice = 500-600 calories per pound). I would have been wiser to begin the process of cyborg-ization. Once I convert into a machine a single meal (lithium air combo #4) will keep me running for years.

    http://www.unitconversion.org/energy/calories-it-to-watt-hours-conversion.html

    • http://cleantechnica.com/ Zachary Shahan

      lol. :D

    • Ross

      On the other side of the equation non-biological machines are much less efficient at using energy.

      • Captivation

        Good point. Unfortunately efficiency has never been my strong suit. The only way to be efficient is to plan, and once I start planning nothing ever gets done. :)

        • http://cleantechnica.com/ Zachary Shahan

          lol. literally. thanks for keeping things lighthearted here :D

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