Leading the Charge for Better Batteries. (Innovations)

Article excerpt

The worldwide market for batteries in 2001 was estimated at $37.7 billion, according to The Powers Review, Year 2000 Battery Industry Developments, prepared by Donald M. MacArthur and George E. Blomgren, and in 1998 alone, more than three billion household and industrial batteries were sold in the United States, the top three markets being cell phones, notebook computers, and power tools. Each year, millions of batteries are disposed of, and therein lies one of the serious environmental issues confronting the electronics industry--some of these batteries contain substances such as lead and cadmium that under certain conditions can leach out of landfills into water causing serious environmental health problems. Inhaled cadmium, according to the Agency for Toxic Substances and Disease Registry (ATSDR), can cause lung damage and death, whereas long-term exposure can cause kidney disease. According to the Department of Health and Human Services, cadmium "may reasonably be anticipated to be a carcinogen." Lead, according to the ATSDR, can cause damage to the nervous system, kidneys, and reproductive system.

The battery industry and equipment manufacturers created the Rechargeable Battery Recycling Corporation in 1994 to recover used rechargeable batteries, but that addresses only part of the equation. The goal now is twofold: to make batteries last longer and to find more environmentally friendly substitutes for their harmful components.

One innovative approach is known as the zinc-air battery, which, rather than using potentially harmful reactants, relies on the oxygen existing in the air to create energy. The cell contains no significantly toxic compounds, and is neither highly reactive nor flammable. Frank Harris, vice president of marketing and licensing for AER Energy Resources in Smyrna, Georgia, which has designed a zinc-air battery, says, "It's important to be a realist about batteries. Batteries have metals in them, and because of that, you'll never have a battery that's truly `green.' The goal is to make that metal as environmentally friendly as possible. For example, zinc [with no added mercury] is more benign than heavy metals used in some types of batteries."

One limitation of the zinc-air battery, however, is that constant contact with the ambient air can either dry up the zinc gel or flood it with water vapor, thus rendering the battery much less potent. AER has found a way around that problem with its proprietary "Diffusion Air Manager" to isolate the battery from air during storage. Built into a battery pack, as opposed to a single battery, the Air Manager turns on when the battery is in use, forcing air through an air inlet tube to start the chemical reaction, and the fan/tube combination minimizes the diffusion of air into and out of the battery when stored or not in use. According to Harris, the manager coupled with new cell design yields a longer-lasting battery with much higher energy density, or ratio of energy to weight or volume.

Nickel-Metal Hydride

One battery component of concern to the industry is cobalt, typically obtained as a by-product of manufacturing nickel. Cobalt can cause asthma and pneumonia, and the International Agency for Research on Cancer has labeled it a "possible human carcinogen." Cobalt is used in a battery electrode because of its propensity for picking up electrons. James Reilly, a guest scientist with Brookhaven National Laboratory's Department of Energy Sciences and Technology in Upton, New York, is part of a team working to find new alloys for use as electrodes--alloys that will last longer and that use more benign substances. Reilly's team was recently awarded a patent for a new electrode alloy that uses lanthanum, nickel, and tin as a replacement for cobalt.

"Nickel-metal hydride batteries are very nice batteries," says Reilly. "They have a much higher energy density than NiCads [nickel-cadmium batteries], and they're more benign. …