As hybrid and electric cars charger become a more viable source of transportation, a debate has sprung up over lithium ion vs. Ni-Mh batteries. Two competing battery technologies have made their way into passenger hybrid and electric cars. Each lithium ion and Ni-Mh batteries have their advantages and disadvantages, but which is a better fit for hybrids and for electrics?

 

To get scientific for a moment, a lithium ion battery is created when lithium moves from the negative to positive point when discharging and the positive to negative point while charging. The result? A rechargeable battery with great shelf life and power ratio, at the detriment of being difficult and costly to produce, as well as unstable. Lithium ion batteries are used in everything from your cell phone to the most high-end electric cars of the day, and while they are still more expensive to produce vs. Ni-Mh batteries, costs are falling.

 

Ni-Mh stands for nickel-metal hydride batteries. This form of battery uses a nickel metal allow to absorb hydrogen at the negative point, allowing the batteries to hold a charge. While they are more stable than lithium ion batteries and cost less to produce, their disadvantages come by way of greater weight to form the same power output, and shorter lifespan with increased maintenance when compared with lithium ion batteries.

 

Ni-Mh batteries have been used for many years as the most common type of rechargeable consumer electronics battery at AA, 9V and other common capacities.

 

The most famous example of a hybrid car using lithium ion batteries is the Chevrolet Volt, which is scheduled to start production in late 2010. Though the Volt has not hit dealerships yet, Chevrolet's promise of lithium ion cells are a big reason why the Volt is able to travel for 40 miles or so on battery energy alone.

 

Also, most of the super high-end electric cars use lithium ion batteries, from the Tesla Roadster and new Tesla Model S to the Fisker Karma luxury electric car. Still, the cost to produce lithium ion batteries, and to produce them to operate safely in car applications, has caused the mass-market hybrid vendors to shy away.

 

Ni-Mh batteries are used by the mass-market hybrids of the day, primarily due to the fact that lithium ion batteries are still prohibitively expensive in cars the automakers hope to sell at a competitive price point. Because these hybrid cars use regenerative systems to recharge the battery as the car moves and brakes, the lower power density when compared with lithium ion batteries is not as much of an issue. The Toyota Prius and Honda Insight, in all their generations, use Ni-Mh batteries as their primary energy storage system.

 

The biggest factor currently affecting the lithium ion vs. Ni-Mh debate is cost. Lithium ion batteries, at capacities large enough to be useful in hybrid or electric cars, are still far more expensive to produce. Still, lithium ion batteries carry a much greater amount of charge than the alternative. Unless some other battery technology comes along that blows lithium ion and Ni-Mh batteries out of the water, expect the future to go to lithium ion as production costs come down.