Waterproof Lithium-Air Battery

IBM recently announced imperial ambitions to conquer lithium-air battery technology; now, TR gives the nuts and bolts on this hopeful beauty...

A company based in Berkeley, CA, is developing lightweight, high-energy batteries that can use the surrounding air as a cathode. PolyPlus is partnering with a manufacturing firm to develop single-use lithium metal-air batteries for the government, and it expects these batteries to be on the market within a few
years. The company also has rechargeable lithium metal-air batteries in the
early stages of development that could eventually power electric vehicles that can go for longer in between charges.

Lithium-metal batteries approach the energy density of fuel cells without the plumbing needed for these devices; in theory, the maximum energy density is
more than 5,000 watt-hours per kilogram, or more than 10 times that of today's
lithium-ion batteries. Lithium metal-air batteries are also very lightweight
because it's not necessary to carry a second reactant. Lithium metal is "the
holy-grail battery material," says Steven Visco, chief technical officer and
founder of PolyPlus.

[...]

Using lithium metal as a battery electrode, however, has proved problematic, mainly because the material reacts rapidly and violently with water. "People have thought about lithium-air batteries for decades, but there's always water in the air," says Visco. Exposure to even traces of water rapidly degrades the material.

PolyPlus has solved this problem by developing what the company calls a "protected lithium electrode." The device consists of a flat, rectangular piece of lithium metal overlaid on either side with a ceramic electrolyte material called lisicon. The solid electrolyte is impermeable to water but lets lithium ions pass through. Another coating protects the electrolyte from reacting with the lithium metal. And finally, the edges of the device are sealed with an aluminum-polymer laminate similar to a potato-chip bag. The laminate provides a watertight seal, and it's flexible, so it doesn't create any strain when the electrode shrinks with use.

When the lithium-metal electrode is placed in water, lithium ions leak out and react with oxygen dissolved in the water or with the water itself. To make a lithium metal-air battery, the device is fitted with a gas-diffusion electrode similar to those used for zinc metal-air hearing-aid batteries. When the battery is switched on, the electrode draws in oxygen through the membrane to react with the lithium ions. But unlike hearing-aid batteries, these devices won't self-discharge over time. "You can leave the battery on the shelf for months and expect it to work because the membrane protects it," says Visco. And because they're based on high-energy lithium metal, these batteries last much longer and are more lighter than zinc-air batteries.

[...]

PolyPlus is currently testing lithium metal-seawater batteries in conjunction with the Monterey Bay Aquarium Research Institute to determine whether they can withstand real working conditions. One concern is that microorganisms in the ocean will grow on the batteries' surface and impair their operation, although preliminary tests have produced good results.

The single-use batteries made by the company employ a piece of lithium metal about two centimeters squared and three millimeters thick; they have a storage capacity close to that of the lithium-ion batteries in today's laptops at one-fifth the weight. The company has partnered with battery manufacturer Quallion to produce batteries based on PolyPlus's electrode designs and will make batteries under contract for an undisclosed government agency. Quallion says that lithium-metal electrodes can be processed using much of the infrastructure already in place for making lithium-ion batteries. "Certain precautions are needed to handle the material, but there are no tricks to it," says Beach.

- Brewskie

This EV Battery Will Outlast Your Dog

This article is from several weeks back, but it's worth noting. Read by clicking here and find out how long this bad boy lasted in a two-year test run:

When it comes to electric vehicles, critics have referred time and again to the fact that the death and replacement of batteries nullifies any savings made at the pump. With a battery’s limited lifespan, and battery prices still high, drivers may not be saving much. However, recent tests by battery provider Southern California Edison (SCE) show.

Over the past two and a half years, SCE has been testing a lithium-ion battery sub-pack. And the results are incredible. The lithium-ion battery has displayed remarkable longevity, surviving 180, 000 miles with no significant deterioration. With the average family vehicle traveling less than 15,000 miles per year, this test holds great significance. This dramatic increase in the life expectancy of an EV battery pulls the cost equation more convincingly on the EV’s side.

[...]

The battery, a Johnson Control-Saft lithium-ion battery subpack, was tested in a commercial delivery van in a laboratory setting at SCE’s Electric Vehicle Testing Center in Pomona, CA. The battery subpack is one sixth of the actual battery size used in a plug-in hybrid electric vehicle.With such remarkable test results, and testing still in progress on the subpack, the U.S. Department of Energy has asked SCE to test the battery’s viability for passenger car performance.

The Department of Energy supplied a full sized battery for further testing.

This will be one of the posts I will refer to when I (eventually - depends on the schedule) get around to doing a future post currently in mind: Why Electric Car Critics are Dead Wrong. Gotta roast Simmons again, though.

- Brewskie

Spin Batteries: the Electromagnetic Batteries

(Hat tip: Oil is Mastery)

From Science Daily:

Researchers at the University of Miami and at the Universities of Tokyo and Tohoku, Japan, have been able to prove the existence of a "spin battery," a battery that is "charged" by applying a large magnetic field to nano-magnets in a device called a magnetic tunnel junction (MTJ).

The new technology is a step towards the creation of computer hard drives with no moving parts, which would be much faster, less expensive and use less energy than current ones. In the future, the new battery could be developed to power cars.

[...]

The device created by University of Miami Physicist Stewart E. Barnes, of the College of Arts and Sciences and his collaborators can store energy in magnets rather than through chemical reactions. Like a winding up toy car, the spin battery is "wound up" by applying a large magnetic field -- no chemistry involved. The device is potentially better than anything found so far, said Barnes.

[...]

The secret behind this technology is the use of nano-magnets to induce an electromotive force. It uses the same principles as those in a conventional battery, except in a more direct fashion. The energy stored in a battery, be it in an iPod or an electric car, is in the form of chemical energy. When something is turned "on" there is a chemical reaction which occurs and produces an electric current. The new technology converts the magnetic energy directly into electrical energy, without a chemical reaction. The electrical current made in this process is called a spin polarized current and finds use in a new technology called "spintronics."

The new discovery advances our understanding of the way magnets work and its immediate application is to use the MTJs as electronic elements which work in different ways to conventional transistors. Although the actual device has a
diameter about that of a human hair and cannot even light up an LED (light-emitting diode--a light source used as electronic component), the energy that might be stored in this way could potentially run a car for miles. The possibilities are endless, Barnes said.

- Brewskie