PolyPlus named Edison Awards finalist on lithium batteries for 500+ mile electric cars
By David Herron on Thu, 02/16/2012 - 18:11
for Torque News
The PolyPlus technology enables lithium-metal-air or lithium-metal-water based batteries with a game-changing jump in energy density over todays lithium-ion batteries, and could bring us to the nirvana of 500 mile range electric cars.
Supposedly the achilles heel of electric cars is the range, and even though electric car owners know range anxiety disappears after a week of ownership, having a longer electric driving range would be handy. Tesla Motors repeatedly proves that a long range electric car is simply a matter of squeezing enough kilowatt-hours of storage onto the car, and then being able to charge a high enough price for the car to pay for the battery pack. Berkeley CA based PolyPlus is developing lithium-air and lithium-water battery technology to make it more practically possible to carry enough kilowatt-hours on-board a car to go 500 miles or more on a charge.
Today PolyPlus announced they'd been selected as a finalist in the Power Generation/Utilization category of the 2012 Edison Best New Product Awards. The awards are named after famed inventor, Thomas Alva Edison. Among Edison's own inventions was a nickel-iron battery that was to be sold in electric cars manufactured by Ford, if it weren't for a mysterious fire that destroyed the Edison factory complex.
Lithium is a highly reactive metal which is known to do catastrophic things when exposed to air or water. Lithium is not found in nature as a pure metal, but always bound to other chemicals. Lithium Ion battery chemistries are a way of binding lithium to other chemicals in a battery for safety (and other) purposes, but this comes at the cost of an energy density much lower than the theoretical maximums. The PolyPlus technology for lithium-air and lithium-water creates the same safety, while maintaining a very high energy density.
Energy density is the amount of energy (watt-hours) per kilogram of battery weight. Typical lithium-ion batteries used in cars today have energy densities in the 150-250 watt-hours per kilogram range. The PolyPlus lithium-water battery has achieved the highest recorded energy density of 1,300 Watt-hours/kilogram, or an almost 10x improvement over current lithium-ion batteries.
To put this into perspective, the Nissan Leaf has a 24 kilowatt-hour battery pack for a nearly 100 mile range. It's battery pack will weigh in the neighborhood of 96-160 kilograms. Using the 1300 watt-hours/kg energy density PolyPlus reports, storing the same energy storage would weigh 19 kilograms, and a 96 kilogram battery pack would carry 125 kilowatt-hours of energy storage, for 5x the energy carried on todays Nissan Leaf, which should offer a nearly 500 mile range.
PolyPlus is currently testing samples of its lithium-water battery and expects the product to be commercially available in 2013.
On the company's website, PolyPlus says that lithium-air batteries have a theoretical energy density of 10,000 watt-hours/kilogram, an energy density that's capable of powering an electric car for a full cross-country trip. Or, more practically, would improve the feasibility of electric big trucks and the like. But achieving anything close to this theoretical density is a ways off in the future. PolyPlus projects the energy density for commercial lithium-air batteries to be 1000 watt-hours per kilogram.
The breakthrough technology is what PolyPlus calls a "protected lithium electrode" (PLE), that remain stable in a broad range of electrolyte solutions. The PLE technology encapsulates lithium metal sealed in a a solid electrolyte. The electrolyte is conductive to lithium ions, but impervious to liquids and gasses, keeping the water or air from touching the lithium.
In the near term PolyPlus says they'll first commercialize non-rechargeable lithium-air and lithium-water batteries, then work on commercializing rechargeable batteries later.
We should note that fast charging of a 125 kilowatt-hour battery pack will require enormous electrical supplies.
Winners of the Gold, Silver and Bronze Edison Awards will be announced April 26, 2012 at the Capitale ballroom in New York City. The awards program occurs over a period of two days and includes a "Meet the Innovators Forum" and an "Innovator's Showcase".
