With the energy density and capacity of rechargeable lithi-um-ion and lithium-polymer cells up by a quarter to a third over the past two and a half years, suppliers of Li-ion batteries are now tackling bigger and more varied applications that include larger and more capable PC-based systems, automobiles and military equipment.
The traditional lithium-ion batteries are also taking greater hold in notebook PCs against nickel cadmium and nickel metal hydride sources, while lithium-polymer types by most accounts are coming on stronger for in-the-field devices. Also, lithium polymer is fast migrating toward the new 42-volt automotive arena and into various hybrid vehicles.
Cost and standardization are among the major forces driving OEM design issues for both Li-ion (liquid electrolyte) and the flat lithium-polymer (gel electrolyte) types, whose initial draw was offering a virtually unlimited number of sizes. In a sign of things to come, there's also an emerging link between Li-ion batteries and alternative energy sources: One lithiumion vendor has demonstrated a fuel-cell prototype for PCs that's slated to hit the market before the end of next year.
Consumer cost is drifting down, amid a mild company shakeout in what is still a largely consumer-oriented OEM business. There's also been some change in product and marketing focus for a few participants. Practical economics more than ever dictate product paths, and thus there's also a consolidation of form factors for both cylindrical and prismatic (rectangular) shapes.
"The cylindrical lithium ion is still king on the notebook PC side," said Hameed Chaudhury, marketing manager for the energy division at Sony Corp. (Park Ridge, NJ). At the same time, he said, "lithium polymer [is] coming on strong in PDAs and cellular, because these portable devices have color displays and do more, so there's less space for batteries."
The capacity for a standard 18-mm (cylindrical) Li-ion battery has gone from about 1,800 milliampere-hours in 2000 to about 2,400 mA-hr. now. Polymers for a given form factor have improved even more, Chaudhury said. "The industry seems to be focusing on two standard polymer footprints: 50 x 34 and 30 x 48 mm. Two years ago, there were more than 20 different battery flavors."
Sony's major gains have come in improving battery capacity at low environmental temperatures (down to -20 degrees C) by about 20 percent over two years ago, Chaudhury said, and by securing gains in cycle life, safety and mechanical robustness.
Japanese-based companies, said to number several hundred, hold a generally acknowledged advantage when it comes to the consumer and wireless markets. To keep their edge, they've kept close tabs on the basic consumer areas, by boosting the capacity of the standard 18650 Li-ion cell, long viewed as a primary building block for notebooks. Sanyo Energy (San Diego), for example, has a 2.2-A-hr. cell and expects to have a much more capable device available by the beginning of next year, said senior vice president Joe Carcone. "Materials breakthroughs that apply to both the anode and cathode are on the horizon, maybe a year or two out," he said. Panasonic/Matsushita (Elgin, Ill.) is another major player.
Most companies now also have both rechargeable Li-ion and advanced rechargeable lithium battery programs in place, the latter often implying lithium polymer. Rechargeable advanced lithium batteries from Toshiba Corp. (Irvine, Calif.), for instance, are polymerlike sources that promise significant increases in capacity. The company bases its AdlB battery family around a proprietary hybrid electrolyte and the gradual implementation of nickel-oxide electrodes in its system. One goal is to improve the safety of the battery's basic construction and, ideally, to minimize the need for protective circuit modules, which in turn will save on cost and space.
With consumer markets strong, North American suppliers are making strides of their own. "The active push in cell phones is away from NiMH and toward lithium ion," said Ralph Wise, product manager at Ultralife Batteries Inc. (Newark, N.Y.), which makes both Li-ion and lithium-polymer types for a wide range of applications. "NiMH is simply not optimized for cell phones," Wise said, referring to the portable-size batteries. "Lithium-ion batteries are still most widely used; the polymers are picking up a bit, though," he said, noting the leap in materials research with various intermetallic compounds. "Standardization and cost are the driving issues. The number of package footprints is down to a very few, because a lot of different products make design engineers nervous. All of this is driving costs lower."
Ultralife says it will boost the capacity for the industry-standard 18650 Li-ion cell, viewed as a primary building block for notebooks, to 2.4 A-h by the end of the year. But more important, Ultralife sees great opportunity right now in bigger pastures.
Indeed, Li-ion sources are moving on to larger projects and new horizons. Electrovaya (Mississauga, Ont.) says it now can deliver its 160-watt-hour PowerPad 160 SuperPolymer battery packs in production quantities to power notebook computers from 12 to 16 hours. The company, previously called Electrofuel, also offers its PowerPad 120 and 80 products for smaller-density, more-cost-sensitive applications. In somewhat of a departure for companies in the Li-ion business, Electrovaya has developed its own line of Scribbler Tablet PCs. Other major Canadian companies include E-One Moli Energy (Maple Ridge, B.C.), which ships a broad line of battery products for the consumer market.
Lithium polymer's applications extend to automotive and military markets, where U.S.-based battery makers sense an edge. "Lithium-polymer technology provides perhaps a threefold improvement over traditional lead-acid batteries," said Joe Lamoreux, vice president and general manager at Val-ence Technology (Henderson, Nev.). Larger systems usually beget larger technical challenges, and perhaps lithium's biggest challenge is safety.
In polymers, designers are further pursuing the advantages of woundtype construction instead of the traditional Bellcore "stacked" construction. Valence, noted for its solid (vs. gel) polymer battery, says it has moreover solved a safety problem associated with the larger cells.
"Historically, cobalt oxide is used for the cathode, but it's thermally unstable; there can be thermal runaway and sometimes unextinguishable fires," Lamoreux explained. Valence thus builds its Saphion wound-cell technology around a phosphate-based cathode material.
"We've been unable to provoke a failure with it," said Lamoreux, which makes the cells particularly attractive for military applications. The energy delivered from a cell using such a system is reportedly less than with cobalt oxide, but second-generation products are closing the gap, he said. Valence, which has expanded into the consumer market, shipped its newest product late last year, a 130-W-hr. flat battery for notebook computers.
Eye on hybrids
Automotive applications, long eyed as fruitful ground for Li-ion power, are now coming into prime time. "The trends in automotive are clear," said Ron Turi, director of product development and applications at Lithium Technology (Plymouth Meeting, Pa.), which has long concentrated on the larger applications and has now merged with Gaia, a German specialist in extrusion-type polymer technology for batteries used in 42-V automotives and hybrid electric vehicles.
"It's toward electronics, and away from pulleys and drives to secure a 10 to 15 percent increase in fuel economy," Turi said. "Of course, there's not a lot of propulsion [accelerating, hill climbing] in the 42-V systems. You need higher voltage for propulsion," he said, referring to the so-called hybrid vehicles. "Honda and Civic use 144 V, and Toyota has a 288-V system."
To satisfy both areas, Lithium Technology has developed a 3.6-V, 9-A-hr. cell in a soft pack and a metal-encased, hermetically sealed 3.6-V, 27-A-hr. cell as building blocks for 42-V batteries. The company's 42-V, 27-A-hr. battery, for instance, packs 10 of the 3.6-V, 27-A-hr. metal foil cells and control electronics in a rectangular case that resembles a traditional lead-acid battery.
Lithium Technology says it is also developing a 144-V, 7-A-hr. battery.
Applications for lithium polymers extend toward some very harsh military environments. Alliant TechSystems, a military contractor that has worked with Valence Technology for several years, initially to explore military applications, is now looking at Valence's Saphion process for use in very stringent environments such as submarines.
Ultralife Batteries, for its part, also continues to develop power sources in its UBI and BA lines to meet stringent military requirements.
E-One Moli Energy
Lithium Technology Corp.
Panasonic/Matsushita Battery Industrial Co.
Toshiba America Electronic Components
Ultralife Batteries Inc.