Electric vehicles can take hours to recharge, making cross-country road trips a challenge. But researchers at the Fraunhofer Institute for Chemical Technology in Germany say they've got a potential solution: flow batteries.

This type of battery uses two electrolytes rather than the solid electrodes used in lithium ion batteries. Recharging them is as fast as pumping out depleted electrolytes and replacing them with fresh ones--it wouldn't take longer than refilling a gas tank. One of the problems with flow batteries, though, has been that they only store about a quarter of the energy as lithium ion batteries--you'd have to recharge a lot, making them impractical. The Fraunhofer researchers say they've improved the energy storage to match lithium ion batteries--still not as good as with gasoline, but a great improvement. Some lithium ion EVs get over 200 miles on a charge.

But here's the catch: one of the reasons hydrogen fuel cell vehicles have come under fire recently is that you need to install a large infrastructure for distributing and dispensing hydrogen. A flow battery system would have a similar problem. You'd need to install special refueling stations where the spend electrolytes can be recharged and dispensed.

Last week Nissan showed off the battery and drivetrain platform for its upcoming electric vehicle. Now it's revealed the car itself--the Leaf.

This zero-emissions vehicle, which has a range of 100 miles on a charge, will go on sale next year in Japan, the United States, and Europe. It will be powered by a lithium manganese battery developed in a joint venture between Nissan and NEC. Manganese-based lithium ion batteries are popular with automakers (GM plans to use one in the Volt) because they're more stable than the cobalt oxide batteries commonly used in laptops and other portable electronics.

Nissan is taking a markedly different strategy than companies such as Toyota, GM, and Chrysler, which have emphasized hybrid vehicles that can run on both electricity and gasoline. Even the Volt, which GM is describing as an electric vehicle, has an onboard gasoline generator that kicks in after 40 miles of driving to recharge its battery. Because gasoline stores orders of magnitude more energy than batteries, such vehicles can have longer range than pure battery electric vehicles like Nissan's Leaf. What's more, fuel tanks can be refilled much faster than batteries can be recharged, at least without special electrical connections, making long-distance road trips easier. (Electric vehicle enthusiasts like to brag about cross-country trips, but these require careful planning--it's good to find RV parks equipped with 220-volt outlets--and a willingness to take frequent breaks while the car charges.)

Nissan has been working with a company called Better Place on a strategy for extending the range of EVs. The idea is to build battery swap stations along major highways. Drive in and a simple robot takes out your car's depleted battery and inserts a charged one, and you're quickly on your way again. Nissan demonstrated one version of a swap station in May.

But it wasn't immediately clear whether the Leaf would be compatible with swap stations. A spokesperson for Nissan said that the company doesn't plan to use a swap strategy in the United States, but she expects the Leaf could be used with swap stations in other countries. She said she'd get back to me to confirm. (If she does, I'll add that here.)

Many EV supporters say it doesn't make sense to buy a car with a gasoline engine and fuel tank as well as an electric motor and battery pack. After all, most of the time either one or the other is just dead weight, sitting there unused. They say, if you commute less than 80 miles each day, buy an EV. Then, for those relatively rare occasions when a longer range is required, rent a car. Or use the EV as a second vehicle.

But one of the most expensive parts of an EV is the battery, and most people actually commute less than 40 miles a day. If you can make do with a battery pack half the size, you could save money, even with the added cost of a gasoline generator. So either strategy--pure EV or hybrid--could make sense.

Today in Tokyo, Nissan showed off a prototype of its electric-vehicle battery platform incorporated into one of its existing vehicles, the Tiida.

The platform will be incorporated into a new vehicle body that will be unveiled at the beginning of August. It consists of a highly rigid body (designed to reduce vibrations and increase the car's durability), an electric motor, and a lithium-ion battery pack built into the floor of the car so that it doesn't eat into cargo space. The production version of the vehicle will go on sale next year, the company says, and get 160 kilometers--100 miles--on a charge.

That short range could be one reason why the company is also marketing a new "EV-IT" system, equipping the electric vehicle with information-technology features to allay range anxiety. These include a map that shows the maximum distance the car can drive based on its current state of charge, as well as the locations of charging stations within reach. The system can also be set so that the vehicle charges at night, which could save people money if utilities start charging rates that vary by the time of day. The system also can send a message to the driver's cell phone when charging is complete.