CarsElectric cars are a game-changing technology with an Achilles’ heel — the battery.

Current batteries are expensive and have limited range, making it hard to drive significant distances without stopping to recharge. Experts agree consumers will never fully embrace electric vehicles until they can travel as far as a gas-powered car on a single charge.

So the global race is on to build a better lithium-ion battery, one that pulls off the herculean feat of extending range while being long-lasting, affordable, quick-charging and safe.

In Asia, governments and big battery companies are investing heavily in next-generation battery technology, while in the United States much of the cutting-edge research is being performed at Department of Energy labs and universities. The San Francisco Bay Area — home to Palo Alto, Calif.-based Tesla Motors, Lawrence Berkeley National Laboratory and two dozen battery startups — has emerged as one of the nation’s leading hubs of battery innovation.

“Transportation is going to go electric, and batteries have become a real critical technology,” said Steve Visco, chief technology officer of PolyPlus, a startup that was spun out of the Berkeley lab. “The Chinese government is subsidizing a lot of battery research, and in Japan the companies have 10-, 20- and 30-year technology road maps.”

The stakes are enormous. President Barack Obama wants to see 1 million electric vehicles on America’s highways by 2015, but many say that goal will be hard to reach until range improves.

“The perception of range anxiety is a real challenge for us,” Renault-Nissan CEO Carlos Ghosn, whose company makes the all-electric Nissan Leaf, said during a visit to Stanford University last month. “People are anxious because it is a double dip — the range is limited, and then if I am stuck, where can I charge?”

Batteries are complex systems that convert stored chemical energy into electricity. Researchers say advances often involve trade-offs: Improving range may result in skyrocketing costs, or a shorter battery life.

“It is a very humbling experience to work on batteries,” said Venkat Srinivasan, a scientist who leads the highly regarded Batteries for Advanced Transportation Technologies team at the Berkeley lab. “To make a good battery is incredibly hard, and to mass-produce it is even harder. If you shoot for one improvement, you usually lose out on something else, and you can’t compromise on safety. If we could double the energy density, that would be a huge breakthrough.”

Measured as kilowatt hours per kilogram or liter, “energy density” determines range: The more watt hours you have, the more miles the car can travel on a single charge. Low-cost, high-energy density batteries are the holy grail.

“If you could go 300 miles on a charge, you’d see significant growth in electric vehicles,” said Michael Omotoso, an auto analyst with J.D. Power and Associates. “We think battery costs will come down due to volume manufacturing, but we don’t see energy density going up that much.”

The Tesla Roadster, Nissan Leaf and Chevrolet Volt all use some form of lithium-ion chemistry in their batteries. First commercialized by Sony in 1991, lithium-ion batteries are widely used in consumer electronics such as laptops and cellphones but are relatively new in cars.

Tesla Motors assembled more than 6,800 lithium-ion cells into a massive 990-pound battery pack for its $109,000 Tesla Roadster — an engineering feat that created the largest lithium-ion pack in the world, with a range of 245 miles.

Tesla’s upcoming Model S sedan, scheduled to hit the market in 2012, will be available with three battery pack options: 160, 230 or 300 miles per charge. Though pricing isn’t final, the cost differences among the three models speaks to battery cost. The 160-mile Model S has a base price of $57,400, before the $7,500 federal tax credit. The 230-mile range option costs about $10,000 more, and the 300-mile range option is $20,000 more — or $77,400.

Consumers want the ability to charge batteries quickly, so the Model S is equipped to charge in 45 minutes if needed. Tesla has not announced the battery warranty.

The bulky battery pack in the Roadster limited the car to two seats with little storage room. For the Model S, a much larger car that seats five adults, Tesla has married the battery pack to the structure of the car, a design that makes the vehicle more aerodynamic.

Santa Monica, Calif.-based Coda Automotive, whose all-electric Coda sedan should launch in California this year, has also incorporated the battery into the structural design of the car. Coda’s 34 kWh battery pack, with an expected range of 90 to 120 miles, is between the rear wheels and the front axle. Coda has not finalized the battery warranty, but it is expected to be at least eight years or 100,000 miles.

“Range is important,” said Phil Gow, Coda’s vice president of battery systems. “But life is important, too. If you have to replace the battery, that’s a significant cost. We wanted to design a car where the battery lasted the life of the vehicle. We have a large battery with a lot of range. Our biggest constraint is cost.”

The basic guts of a battery include a negatively charged anode, a positively charged cathode and the electrolyte. When a battery is fully charged, the lithium ions are concentrated in the anode. As the battery discharges, the ions flow to the cathode and current flows through the electric circuit, releasing energy.

The most commercially popular anode material is graphite; cathodes are usually made of a lithium compound, such as lithium iron phosphate. Many startups are experimenting with battery chemistry and using various materials for the anode or cathode or both.

While there’s talk in the industry of moving “beyond lithium” and using new materials, many expect lithium-ion batteries to remain dominant in the coming decades.

“Everyone is moving rapidly up the technology curve,” said Jim Dunlay, Tesla’s vice president for powertrain hardware engineering. “Lithium-ion is still on a strong trajectory; it hasn’t peaked. We are using better cells, and we’ve learned how to package them more densely together. But it’s not just about building a better battery. A better battery means we have a better car.”

The Obama administration has poured $2.4 billion into electric-vehicle batteries and charging infrastructure in hopes of improving energy density, bringing down costs and creating jobs. Tesla, Nissan and Fisker Automotive have been awarded loans to establish manufacturing facilities, and several other companies were awarded federal ARPA-E grants, which support high-risk, high-reward energy research. PolyPlus received a $5 million ARPA-E grant for its work on a rechargeable lithium-air battery.

“Some of the best minds in the country are now working in this area,” said David Sandalow, the Department of Energy’s assistant secretary for policy and international affairs. “When you combine intellectual capital and financial resources, that’s what happens. It’s a dynamic space to be in.”

Illinois, Massachusetts and Michigan are centers of advanced battery research, and the Bay Area has also emerged as a major player: Tesla Motors will build the Model S at its Fremont, Calif., factory, and several startups have been spun out of the Berkeley lab and Stanford University.

Many battery startups remain in “stealth” mode and have yet to discuss their technology in depth. But they are attracting venture capital funding.

Amprius, based in Mountain View, Calif., uses silicon for the material in the battery anode and raised $25 million in March. Seeo, founded in 2007 with an exclusive license to use advanced technology from the Berkeley lab, is backed by Khosla Ventures, and Envia Systems, a Newark, Calif., startup using manganese in its cathode, raised $17 million from General Motors.

“Everyone is tweaking the materials that are used,” said Srinivasan of the Berkeley lab, who knows of 24 battery startups in the region. “We get emails that say, ‘Hi, we started a battery company, can we come meet with you?’ “

Source: McClatchy-Tribune Information Services.