Laptop batteries have been in the spotlight recently for catching on fire, thanks to manufacturing problems at Sony that have led to a recall of more than 6 million batteries. Once that smoke clears, as it likely will, we're still stuck with the fact that our ability to digitally work (or play) is severely limited by how long our batteries hold a charge. And, unfortunately, that hasn't changed much in recent years. There has been some improvement in the running time of batteries that power notebook computers, cell phones, portable game players, PDAs, and other devices, but not enough. And significant advances aren't in sight.

This is an area of technology begging for a breakthrough. That's why some believe that the computer, communications, and consumer electronics industries need to move away from batteries as we've known them and find new ways to power all the mobile devices people carry around. Some of the ideas seem, well, unusual. How about a hydrogen fuel cell in your cell phone? Or a mini gas-turbine engine in your BlackBerry? These are still far-off notions, but it's going to take this kind of daring experimentation to break out of the lithium-ion box that keeps us reaching for a power cord every few hours.

Turbine Engine On A Chip

MIT researchers are attempting to apply the growing field of power microelectromechanical systems to create tiny gas-turbine engines inside a silicon chip about the size of a quarter. The device in theory would run 10 times longer than batteries of the same weight and let developers create a smaller power source. The miniature microengine would be made using six bonded silicon wafers in which the compressor, combustion chamber, spinning turbine, and other necessary features are pre-etched into the individual layers of silicon. Inside the tiny combustion chamber, the fuel and air would mix and burn. The turbine blades, made of microfabricated materials, would spin at about 20,000 revolutions per second.

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"We have demonstrated that all the different parts work," says Alan Epstein, a professor in the department of aeronautics and astronautics at MIT. "Now the challenge is to get them all to work together in the same place on the same day--the integration."

The miniature power-producing chips will be ready to demo within a year, Epstein predicts. After that, it will take three years or more for a business to use the technology to create a commercial product.

Such a power source, if perfected, will have to clear the hurdles that stand before any technology considered as a general replacement for batteries. Can hundreds of millions of them be manufactured every year at a price that competes with relatively cheap batteries? Will people want to carry around an internal combustion engine in their pockets or purses?

Hydrogen fuel cells are another alternative on the horizon. Don Gervasio, a chemist at Arizona State University, is working on a hydrogen fuel cell that uses a 30% solution of a borohydride compound to create higher levels of hydrogen than in the same volume of liquid hydrogen. The borohydride solution is more stable--and therefore safer--than traditional fuel cells, he says.

"We are doing a cartridge of borohydride in which I could take a match and put it out in the material," says Gervasio, highlighting the safety concerns that any new power source will face. The solution releases its hydrogen as it flows over a catalyst made of ruthenium, and then passes through a membrane and combines with oxygen in the fuel cell, generating electricity.

The approach has had to get past some snags. Early efforts derailed when the hydrogen-generating cells became clogged with an insoluble byproduct. The research team began using ethylene glycol--antifreeze--which didn't affect hydrogen generation, to dissolve the boron oxide. Gervasio says his team is anywhere from one to three years away from a preindustrial prototype, and a commercial product would be some years after that.

Other companies are working on fuel cells that would use a form of liquid methanol. But no one is close to developing a fuel cell that can supply the power needs of a notebook computer, fit in the same small space as a battery, and be made at a cost close to that of a battery.

Limited Choices

Lithium-ion batteries began supplanting nickel metal hydride-based batteries in the 1990s and became the dominate chemistry for laptops and handheld devices by the end of the decade, primarily because lithium ion can store greater amounts of energy in a given cell size and is a much lighter technology than nickel metal hydride. In the past few years, lithium-ion technology has improved 20% to 30% in energy density, allowing a typical laptop battery to last four to five hours, up from about three hours in 2004, according to the Portable Rechargeable Battery Association, a trade group for makers and users of batteries. About 2 billion lithium-ion batteries are manufactured a year.

Most lithium-ion batteries are based on cobalt oxide-based cathodes, which are contained in cells. Because the material contains oxygen, it's quite volatile. If lithium-ion batteries aren't made properly, they can short circuit or overheat, and on rare occasions a stray spark within a battery cell can catch fire. Most of the major notebook makers have recalled Sony-made batteries, and the steady stream of news about battery-replacement programs has called attention to an industry that rarely gets much.

The good news is that the problems appear limited to one manufacturer, Sony, and that most in the battery industry believe the company can and will fix the significant manufacturing errors that led to the problem. Sony says it's already taken steps to prevent a repeat of the problems.

The bad news is that it looks like we're stuck with the current state of technology for a while. Lithium-ion batteries are nearing their theoretical energy density limit, Frost & Sullivan analyst Sara Bradford says in a recent report. But it's unlikely that new alternatives will hit the market soon, and in the short term, only small improvements are expected. "There's really nothing significantly different that's going to happen [with battery technology] for the next two to three years," says David Perlmutter, senior VP and general manager of Intel's mobility group. "Right now, the industry is working primarily on improving the manufacturing and reliability of traditional lithium-ion batteries."

But there are a host of startup companies and academic research efforts under way to provide a little more juice to portable power supplies. (Sony declined to discuss any next-generation battery R&D it has in the works.) The testing and development of alternative battery technologies is being accelerated, and many groups are actively looking for funding, partners, and customers.

Alternative Battery Projects Unhappy with the short charge life of batteries and the tendency of some to overheat? If you're hoping for a quick solution, don't hold your breath. Some advances maybe be forthcoming in 2007, but the real breakthroughs are at least four years away. Here's a sampling of what's under development: Technology Company Pros/Cons Availability Nonvolatile phosphate-based lithium ion Valence Technology Eliminates the potential for an explosion, but getting the technology to meet mainstream specifications and provide extended battery life remains a challenge First drop-in laptop replacements expected in 2007 Nanoscale phosphate-based lithium ion A123Systems Submicron-size particles promise fast recharges and a long useful lifetime, but use in laptops is likely to be years away Use in cell phones expected in 2007 Silver and zinc Zinc Matrix Power Water-based chemistry isn't flammable and provides longer running time than lithium ion; the number of recharges, however, is currently limited Use in laptops and cell phones as soon as 2007 MEMS-based gas-turbine engines Under development by MIT Could eliminate the battery all together, but the microelectromechanical devices remain unproven At least four years from commercial availability Hydrogen fuel cells Widespread experimentation ongoing, including at Arizona State University Has potential in a wide range of applications, with use in handheld electronic devices the farthest from being perfected Five or more years away for portable electronics

Extending Life

With no new technology to change the game, Intel's engineers and researchers work "milliwatt by milliwatt" to find areas in which they can reduce the power demands of the components in a system, Perlmutter says. He estimates each watt of power demand they can remove from a system can extend battery life 25 to 30 minutes.

Another approach to replacing the lithium-ion battery is to reduce the volatility of the current chemistries. Yet that often means shorter battery life, and laptop manufacturers know consumers want the longest possible battery life and are less concerned about the relatively few instances of burning batteries.

"No [laptop provider] has as yet been willing to be the first one on the block to provide their customers with less runtime than their competitors," says Dean Bogues, president of worldwide sales and marketing for Valence Technology, a provider of alternative battery technology. "But the question is, will that technology ever be safe enough? If it was a fixable problem, why hasn't it been taken care of over the past 10 years?"

Chemistry Counts

Valence manufactures and sells a nonvolatile phosphate-based cathode for its lithium-ion batteries, under the brand name of Saphion, which it says greatly reduces the potential for igniting. But it has big shortcomings. Valence's technology operates at 3.2 volts, which would require a redesign or retrofit of existing electronic equipment that uses 3.6-volt batteries.

> Zinc Matrix Power A longer running time comes with a shorter life span

Even worse, while the Valence batteries have a potential useful life that's three times longer than traditional lithium-ion batteries, they provide a running time between charges of about 40% less. A conventional cobalt oxide-based lithium-ion battery might have a four-hour running time, but an equivalent Valence battery would only run around 2.5 hours.

Valence now offers a battery accessory based on its Saphion technology that can plug into a laptop to extend a computer's running time to up to 10 hours, providing computer power during long-range travel for those willing to carry an extra piece of electronics. The N-Charge power system weighs about 3 pounds and also is used in classrooms where power isn't available at every desk and for wireless and portable nursing stations in hospitals.

Valence is working on next-generation Saphion II technology that would operate at 3.6 volts, work as drop-in replacement battery cells for notebook computers, and have only 10% to 15% less running time than conventional lithium-ion batteries, Bogues says. It's scheduled for introduction next year. "If we can provide a safe alternative that gets within about 10% of traditional technology, the market will look to make a shift," he says.

Another phosphate-based lithium-ion technology already in commercial use is A123Systems' nanoscale approach. DeWalt/Black & Decker offers a line of 36-volt power tools that utilize the A123Systems battery technology.

Smaller Is Better

David Vieau, A123Systems' CEO and president, is anxious to expand markets for the nanophosphate technology and says the company is actively talking with cell phone companies--Motorola and Qualcomm are investors--and also is engaged in a project related to hybrid automobiles. But a move into notebook computers looks years away.

In addition to the benefits of phosphate, A123Systems' nanoscale approach reduces the size of individual particles in the battery from an average of 1 micron or larger in conventional lithium-ion technology to 100 nanometers, or about 1/100th the size. Smaller particles can absorb lithium at a greater rate than regular batteries, which lets the battery recharge more quickly. An average charge time of two to three hours for a cell phone could be reduced to five to 10 minutes, Vieau says. And while a typical cell phone battery provides 300 to 400 charge cycles in a lifetime, the A123Systems technology promises 7,000.

> A123Systems Nanoscale could mean 5-minute recharge

Battery companies are trying a wide variety of chemical formulas to find one that duplicates or bests lithium ion. Ross Dueber, president and CEO of Zinc Matrix Power, believes his alternate-chemistry battery will be ready for commercial deployment next year. Intel, which has invested in Zinc Matrix, named the company the winner of the Technology Innovation Accelerated Award for the mobile category at the Intel Developer Forum in September.

The Zinc Matrix approach uses silver and zinc to provide as much as twice the running time of lithium ion, and its water-based chemistry isn't flammable or toxic, Dueber says. The company initially concentrated on military applications, but after receiving investment from Intel two years ago, turned its attention to creating a notebook battery that runs up to 10 hours.

But it has too big a trade-off right now. Dueber says he can create batteries that are about 20% denser in energy than lithium ion, increasing to 50% greater energy density as he ramps up production. But they only last for about 25 recharges, compared with 200 to 250 for today's batteries. The company is working toward around 100 recharges, which, with the longer per-charge life of the zinc-based battery, would move it into the league of lithium ion in total usable life.

"When lithium ion started out about 15 years ago, it could provide about half the cycle life of the nickel metal hydride it was replacing, but it also offered a 30% improvement in runtime, so that was a trade-off consumers were willing to make," he says.

> N-Charge Packed with power but won't fit into a notebook computer

Zinc Matrix plans to work with notebook and cell phone manufacturers to get new designs ready for production next year. Initially, the technology would likely be marketed as a higher-end option for devices such as "road warrior laptops," Dueber says.

History suggests what shows up in high-end equipment will quickly make its way into mainstream gear--if it can be manufactured in large quantities at low cost. That's the challenge: to economically produce a power source that can handle the various needs of the computer, cell phone, and consumer electronic industries, which require billions of batteries each year.

Hopefully, Sony can put an end to the burning laptop problem. But even then, it's looking for the next few years like businesses and consumers will have to live with various performance trade-offs as they wait for the long-lived battery of their dreams.

Photo by MIT