While most hybrids use nickel-metal hydride batteries today, which can store up to 36 watt-hours per pound, they can’t deliver the all-electric range that many automakers want for electric vehicles and some plug-in hybrids, such as GM’s much-anticipated Chevy Volt. Lithium-ions offer more than double the energy density of nickel-metal hydrides, storing up to 81 watt-hours per pound, Ms. Bradford says.
But the batteries are too costly for most vehicles and for grid storage today, she says. Lithium-ion also faces some technical challenges.
For one thing, consumer electronics generally call for longer running times (more energy) while vehicles tend to require higher voltage (more power), says Mr. Furst. Vehicle batteries also need to be able to perform in widely varying temperatures, and need longer life spans than are typically required for consumer electronics.
Then there’s the safety issue: After Dell recalled thousands of laptop batteries in 2006 because of a fire hazard, everyone wants to be sure their batteries won’t burst into flames. “When it comes to motor vehicles, safety is the No. 1 concern,” Furst says. “You can’t have a battery pack blowing up in your car.”
Most of the lithium-ion technologies working to address these issues are focused on new materials, particularly at the cathode of the battery – or the negatively charged part where electrons enter the device – Bradford says.
A123Systems in Watertown, Mass., is one such company. The company, which raised $69 million in April and signed a deal to supply electric-vehicle batteries to Chrysler, is developing batteries with tiny phosphate particles at the cathode, which it claims makes them safer. (Phosphate is used in fire extinguishers.) The company also claims its batteries offer higher energy density; a longer lifespan; and the ability to recharge 90 percent in five minutes, a potentially useful trait for longer trips.