Go ahead and admit it. Don’t be afraid. At some point somewhere, there was a time when you figured all batteries no longer contained mercury. Maybe such a misconception was powered in part due to the widely known legislation that mandated the elimination of mercury from household alkaline batteries in the late 1990s. Maybe it was derived by the name change when cells went from being “mercury oxide” to the somewhat less toxic sounding “zinc air.”
Either way, if you know better, good for you. But if not, you’re not alone, says Philip Cooper, specialty batteries quality assurance manager for St Louis-based Energizer, who calls the belief that hearing aid batteries are without mercury a common one.
“Because years ago,” Cooper says, “the first hearing aid battery we made was silver-oxide. But then the whole industry changed to what was called mercuric-oxide batteries, which had something like 1,000 times more mercury in them than what the current hearing aid battery has. When they were 33 banned and the industry went to zinc-air batteries, there was an assumption that we no longer had mercury in the batteries.”
Tom Begley, division vice president of sales at Rayovac, Madison, Wis, says he has encountered the same misunderstanding.
“We’ve had audiologists and dispensers come up to us and say, ‘Hey, we thought you got rid of mercury 10 years ago, so what is this?’ And the answer is yes, we did get rid of mercury-containing batteries, but there is still a bit of mercury in there.”
Dennis Carpenter, zinc air technical manager with Rayovac, gives perspective and definition to what “a bit” actually means.
“In the past, with mercury-oxide batteries, essentially half the battery was mercury. When manufacturers first went to zinc-air batteries, the amount of mercury involved was around 7% by weight,” Carpenter says. “Today, the most mercury you can put into a battery is 25 milligrams.”
Or roughly 3%. But why not zero milligrams?
“The small amount of mercury that’s in batteries is there for a reason,” Cooper says. “Mercury helps control unwanted gassing reactions that happen during the discharge.”
Begley adds, “Mercury has been a way for battery manufacturers to make a more stable battery that didn’t leak, that didn’t gas, and that provided better performance.”
Suffice it to say, getting rid of such a crucial element entirely would prove a big, expensive, and difficult challenge that for Rayovac began around 1998. Energizer first explored mercury-free territory in the late 1980s.
“By 1990, Energizer was able to develop a mercury-free hearing aid battery,” says Brand Manager Stephen Carlin. “That said, there was a lot of technical development needed to have the battery perform at the level we wanted it to perform.”
Begley can recall a true mercury-free battery being introduced in 1996. “But it failed miserably because no sooner did they unveil it than it started leaking,” he said.
It was 5 years later when Energizer successfully launched its Zero Mercury batteries in Europe.
“Europe is a different market with different legal requirements that they need to hit,” Carlin says. “So when I say they were successful in Europe, it was under the conditions that the market put upon the battery industry. Technical hurdles needed to be attained with the battery regarding the US market that we’ve been working on overcoming the last 7 years.”
The biggest hurdle: pinpointing a replacement element as versatile as mercury.
“Essentially, we had to find another element in the periodic table that had similar properties to mercury from a usability standpoint, an environmental standpoint, and an electrochemical standpoint,” Cooper says. “It was a challenge because in addition to controlling gassing, mercury is a very conductive liquid metal, and from a production standpoint, it’s great to use because you can put it anywhere.”
“It’s a bit like making a cake without eggs,” Carlin says.
“And it took awhile,” Cooper says. “We went through a lot of trial and error. We’d start with our chemists saying, ‘OK, chemically these elements ought to be the right ones.’ Then we would start blending them and putting them into formulations. Some would work OK and some didn’t work at all—batteries were blowing up here and there in labs.”
|Presently, 22 states (red) have some form of anti-mercury legislation pending.|
Begley confirms the trials involved. “A mercury-free battery is a very difficult product to manufacture—and very expensive.”
“Since mercury is very good at suppressing gassing,” Carpenter says, “when you have trace impurities, you bring out gassing in the zinc-air battery. So what you have to do is essentially create a very clean work environment, and that costs money: air-handling systems, brand-new equipment for processing the products. So from a research and development standpoint, it can cost on the order of millions of dollars.”
“And not only that,” Begley adds, “but our suppliers had to do the same thing. Raw material suppliers had to convert their shops and plants so we would have pure products. Initial products had impurities, and that resulted in problems for us. We had to really work closely with them to develop a superior product.”
Rayovac and Energizer are part of the National Electrical Manufacturers Association (NEMA), a consortium that represented them and other battery makers when states began considering the enacting of laws banning mercury from button cell batteries, a product that had been exempted when mercury was initially banned from alkaline batteries, because “manufacturers at that time didn’t know how to take the mercury out and still offer a reliable product to the consumer,” Begley says.
“But with our mercury-containing batteries remaining a very visible consumer product, they became a target,” Carlin said, “and state legislators began crafting laws that would set a date when all batteries would have to be mercury free.”
“There were two states in particular—Connecticut and Maine—that were on the forefront,” Begley says. “One wanted to do a recycling program, and the other wanted to just totally ban the sale of mercury-containing batteries.”
“Without understanding the technical aspects of how to do that,” Cooper points out.
“The big difference between household batteries and button cells is that household batteries have sealed systems that can handle higher internal pressure that comes from gassing,” Carpenter says. “In a zinc-air cell, because it wants oxygen to come in, if you have internal pressure, it impedes that process. So the same amount of gassing that goes on in a button cell is much more detrimental to a cell’s function than to an alkaline battery.”
“We had to point out, as did the other manufacturers, that there is a difference between the two battery systems,” Begley says. “Because if the legislators had their choice, they would have just issued a blanket ban—they’re all gone. Our people took them through the real reasons. We weren’t just out there crying; we couldn’t, nor could the other manufacturers, make a mercury-free product.”
Adds Carpenter, “We’ve pointed out that with a medical device for a handicapped population, if it couldn’t be powered, then we’re doing a disservice and that resonated quite a bit.”
In response to the states’ proposals, NEMA provided a counteroffer.
“NEMA said that before the states start legislating battery companies into doing something they’re presently incapable of doing, allow them to study the issue and come back with a recommended compliance date,” Cooper says. “And so they came back with June 30, 2011, and we said that voluntarily as an industry we can hit that date.”
The states agreed, and later Canada came on board as well. And the penalty come July 1 of that year for companies unsuccessful in their mercury-free development.
“You can’t sell product in Connecticut, Maine, or Canada,” Begley says.
“We suspect most other states will follow,” Carpenter adds.
Presently, there are 22 states with some form of mercury-banning legislation pending. And with more than 2.5 years ahead of the deadline, Energizer and Rayovac are the first two manufacturers to achieve that goal, with Rayovac being the first to announce in March they would be coming out with a mercury-free battery in North America, and Energizer being the first this October to get its Zero Mercury products on the shelves and available to consumers.
Begley expects Rayovac’s mercury-free cells will be available through hearing care professionals under the Rayovac ProLine brand and also through retail outlets under the Rayovac label by some time in the first quarter of 2009.
To anyone wondering about the amount of time between Rayovac’s first announcement and its products’ anticipated arrival, Begley doesn’t see it as a big deal. He sees his company’s patience as a virtue.
Gassing: Gassing is a phenomenon that occurs during the electrolytic process that would otherwise corrode the battery.
Mercury-oxide: Also known as a mercuric-oxide battery. Due to the content of mercury and the resulting environmental concerns, the sale of mercury batteries is banned in many countries. Both ANSI and IEC have withdrawn standards for mercury batteries. Mercury batteries were made in button types for watches, hearing aids, and calculators, and in larger forms for other applications.
NEMA: National Electrical Manufacturers Association. The organization that countered a legislated mercury ban on button cell batteries with a proposed date of June 30, 2011, for companies to voluntarily remove the substance.
Silver-oxide: Also known as silver–zinc batteries, silver-oxide batteries have a long life and a very high energy/weight ratio, but a prohibitive cost for most applications due to the high price of silver.
Zinc-air: These electro chemical batteries are powered by the oxidation of zinc with oxygen from the air. They have high energy densities and are relatively inexpensive to produce. They are used in hearing aids and in experimental electric vehicles.
“Rayovac is committed to providing a world-class mercury-free product, and that takes time,” he says. “In addition, we wanted to provide guidance to Connecticut and Maine that Rayovac was ready and able to supply an environmentally friendly mercury-free battery ahead of schedule. Just today the EPA communicated that a mercury-free button cell will be available. Rayovac’s early announcement will accelerate the conversion to this eco-friendly battery.”
But no one should be wondering why these companies went through all the trouble.
“It was the right thing to do,” Begley says.
“Getting rid of mercury has done a lot for the environment,” Carlin says, “particularly in North America, where there are some 5,300 pounds of mercury that go into the environment from hearing aid batteries—that’s like a Buick every year.”
To put it in perspective, Carlin points out that’s only around 2% of all the mercury expended. And Cooper tells us it’s not going anywhere.
“Mercury is one of these elements that’s kind of omnipotent,” Cooper says. “It’s in the environment, and it’s always going to be there. It never deteriorates.”
But it can be deadly.
“The form we use is pure elemental mercury,” Cooper says, “and in its elemental state it’s not all that toxic. But over a long period of time, it can transform into several different elements, one of which is methyl-mercury. That’s the deadly one. So the trick is to prevent it from ever getting into that state.”
And by eliminating mercury from their products, Energizer and Rayovac have done just that.