In the past three years, the thought of companies like Chevrolet and Nissan selling lithium-ion-powered cars has gone from laughable to old news. Late this year, the plug-in Chevy Volt and pure-electric Nissan Leaf arrive. Carmakers from Ford to Toyota will follow in 2011 and 2012 with new electrified models of their own. In the beginning, the electric-car revolution probably won’t seem so revolutionary: a few thousand cars here and there. As long as automakers and battery companies keep pushing technology forward, however—by scaling up production and developing more-powerful ways to store electricity and power a car with it—the future for cars that plug into the wall will continue to brighten. Here’s where this emerging industry stands today.
Lithium-ion batteries—the dominant technology in forthcoming electric cars—begin when active battery ingredients are combined to form an electrode slurry. A liquid solvent, electrode powder (for the negative electrode, a form of carbon; for the positive, a form of lithium-containing metal oxide or phosphate) and a chemical binder are blended into a paste in what look like industrial pizza-dough mixers.
The coater, a machine reminiscent of a printing press, paints the electrode slurry onto long sheets of metal foil (copper for the negative, aluminum for the positive).
The freshly coated sheets pass through an oven for curing at 200ºF. The oven can be a bottleneck; its size and speed determine the rate of production.
4. Shaping and Cleaning
To make rectangular, “prismatic” batteries, machines chop the long reels of electrode material into paperback-size pieces, which are then compressed, brushed, and vacuumed.
With a piece of porous separator material (it looks like white trash-bag plastic) between them, the positive and negative electrodes are sandwiched together into stacks. The separator prevents short-circuiting while still allowing the electrodes to exchange ions. The stacks go into plastic pouches that are then filled with liquid electrolyte and vacuum-sealed shut. The result is a cell, the building block of a battery.
After pre-charging (just enough juice to start the chemical reaction), the cell is opened, vented, and resealed. Next the cells are charged to 60 percent, then aged for 14 days.
7. Module and Pack Assembly
Cells are bundled together (along with cooling and heating mechanisms, the voltage-monitoring circuitry, and other control systems) to form modules. Modules are then bundled together in a case and wired with additional monitoring circuitry to form the final battery pack, the box that powers a car.
2. A123 Systems
A $249.1-million grant will help the Boston-area company build a cell factory near Detroit, from which it hopes to supply GM, Chrysler and others.
3. Dow Kokam
The Dow Chemical joint venture banked $161 million for a new Michigan lithium-ion factory.
4. Compact Power
A $151.4-million grant will help build a Michigan factory to supply batteries for the Chevy Volt.
EnerDel, a supplier for Volvo and Think, is using its $118.5-million share to build a third EV-battery factory in Indianapolis.
Five amazing, clean technologies that will set us free, in this month's energy-focused issue. Also: how to build a better bomb detector, the robotic toys that are raising your children, a human catapult, the world's smallest arcade, and much more.