The humble battery slims down and charges up

Japan's Matsushita Electric Industrial Company recently made a battery as thin as a postage stamp, and roughly the same dimensions, that could power a microchip inside a credit card for up to five years. The slim cell is part of a rapidly emerging class of batteries that use lithium as a main ingredient -- and is slowly ushering in one of the biggest technological changes in the staid field this century.

Smaller, lighter, and longer-lasting than many conventional batteries, Lilliputian lithium cells are being used in such things as watches, cameras, and computers. Now rechargeable versions are being developed that, enthusiasts claim, might make your ``dustbuster,'' flashlight, or power tools whine and shine longer between ``boosts.''

Eventually they may show up in products used everywhere from space to the ocean deep. But don't toss your trusty old alkaline or nickel-cadmium batteries yet: Lithium has a few problems, too.

``Lithium is the new shining star on the horizon,'' says Robert Morey, editor of Advanced Battery Technology, an industry newsletter.

The battery field is going through significant changes. Innovations usually come volt by painful volt in this change-resistant and technically complex industry. But there has been a surge of research activity in recent years as companies mount a high-stakes -- and high-tech -- race to upgrade this unheralded workhorse of the consumer, military, and industrial worlds.

There's good reason for the interest. Batteries are a booming business: Some $2 billion will be spent in the US this year on cells for tools, toys, and other consumer applications. More than that will go for batteries used in cars and elsewhere.

A chief thrust is to invent cells that are smaller, lighter, more powerful, and, of course, cheaper than current ones. Behind this push for brawnier bantams is the proliferation of portable electrical products and electronic goods. How nifty and nimble these products are hinges partly on how novel are the cells that power them.

Enter lithium. Boosters tout it as something of a Sugar Ray Leonard of the battery world -- light but powerful. It packs more energy into a given space -- two to 10 times as much as ordinary carbon-zinc batteries -- and can sit unused for years without losing much power. It also works at greater temperature ranges than conventional batteries. ``Lithium is the newest and most interesting'' development in the battery field, says Sumner Wolsky, a Boca Raton, Fla., consultant. ``But you can't write off alkaline batteries yet.''

For now, lithium is a mere flyspeck in the overall cell market: less than 1 percent of the United States' $2 billion-a-year primary battery market (primary cells are those that are made fully charged and have to be discarded when their power is used up). But lithium batteries are one of the fastest-growing segments of the industry.

Their peculiar pluses have made them attractive for specialized niches beyond consumer goods. The ability to tolerate temperature swings has made them ideal for underwater devices. Longevity has made them popular for heart pacemakers: They need be changed every five to 10 years, as opposed to a two-year life span for the old batteries. The military is a big user, in communications equipment and for backup power in missile silos.

A bigger bonanza, though, may await whoever first hatches a rechargeable lithium cell. In theory, it would open up a host of product possibilities: from longer-lasting portable vacuum cleaners to trim battery packs. Matsushita expects to start selling one later this year, for use as a power backup in such things as videocassette recorders. Most big batterymakers are working on rechargeable lithium cells.

Lithium has its warts, though. One is that the metal is highly reactive, and there is continuing concern about safety. Some early primary cells caused fires and explosions. Although manufacturers contend they have solved these problems, skeptics argue that more needs to be done in safely packaging the cells, particularly for consumer use.

Cost is another snag. A third is that lithium, while packing a lot of energy, often doesn't have the high-strength current needed to run many devices. ``If you run a flashlight, fine,'' says John Hodgman, manager of engineering at the General Electric Company. ``But if it's anything motor-driven, there's not enough current there.''

Other novel battery designs, meanwhile, are surfacing. Rayovac Corporation recently came up with a new primary zinc-air battery (using oxygen in the air as its cathode) that may boost the life of hearing-aid-size cells 30 percent. In car batteries, smaller and slimmer is still the aim: An Australian company recently hatched a lead-acid battery that is about half the size of conventional ones.

Also in rechargeables, exotic products like Gulf & Western's zinc-chlorine battery, which for years was going to usher in an era of mass-produced electric cars, are still being worked on. But progress is incremental -- a reminder that, in the complex battery business, breakthroughs aren't ever-ready. A Tuesday column