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Small and Rechargeable Battery Tour PDF Print E-mail
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Tuesday, 15 January 2008
Welcome to the Small & Rechargeable Battery Tour

This tour will guide you through different types of small batteries, both disposable and rechargeable, and explain their environmental impact. This tour will provide you with information you need to make informed decisions when purchasing and disposing of small batteries.

How do small batteries work?

There are many types of small batteries, some rechargeable, others disposable. No matter the type, they all function based on the same electrochemical principals. Inside the battery, different chemicals and metals react to produce electrons which power devices such as flash lights and digital cameras.


Types of Disposable Batteries

   
Leclanché Cells:
 

These are more commonly known as zinc carbon cells or dry cells. They have a zinc or carbon anode and often use Manganese Dioxide (MnO2) for the cathode. The electrolyte is often ammonium chloride or zinc chloride dissolved in water. Though the name may be unfamiliar to many people, the battery it describes is very well known. You probably have a drawer full of these batteries for your kids toys and flashlights. The Leclanché cell has been around since about 1860, and until World War II, was the only one in wide use. It is still the most commonly used battery because of its low cost.

In Leclanché cells, the electrolyte consists of roughly 26% NH4Cl (ammonium chloride), 8% ZnCl2 (zinc chloride), and 66% water. For the chemists among you,  the cell reaction can be expressed as:

Zn + 2MnO2 +2NH4Cl —> 2MnOOH + Zn(NH3)2Cl2 E=1.26
 

Alkaline Cells:
These batteries are becoming more and more popular. Though they are more expensive than Leclanché cells, they offer better performance and longer life. Alkaline cells use Zinc powder for the anode, but they still use Manganese dioxide (MnO2) powder for the cathode, just like Leclanché cells. The electrolyte in these batteries has been changed to Potassium hydroxide (KOH). Again, many people have a drawer or cabinet full of these batteries for toys and flashlights.
This battery gets its name from the alkaline solution used as electrolytes. On the shelf since the early ’60s, the alkaline cell has grown in popularity, becoming the zinc-carbon cell's greatest competitor. Alkaline cells have many advantages over zinc-carbon batteries. Many of us have opened a flashlight that's been under the car seat or in the garage for a long time, and many of us have been greeted with a fuzzy green mess. Alkaline batteries tend not to leak like zinc-carbon batteries, and as a result, have a longer shelf life. They also perform well over a wider temperature range. This improved performance makes the alkaline battery more cost effective than the zinc-carbon cells.

Again for the chemists, the total reaction can be expressed as:

Zn + 2MnO2 —> ZnO + Mn2O3 E=1.5 V
 


Mercury Oxide Cells:
These batteries, often called button cells, are commonly used in watches, hearing aids, and even ties with flashing lights! There are very few manufacturers of these batteries because of the high risk to the environment. These cells come in two common "flavors": cadmium/mercuric oxide and zinc/mercuric oxide. The anodes tend to be either zinc or cadmium, the cathodes are mercuric oxide, with a potassium hydroxide electrolyte.

Sick of chemistry yet? The reaction for these batteries will be one of the following depending on the type of anode:

Zn + HgO = ZnO + Hg

Cd + HgO + H2O = Cd(OH2) + Hg


Types of Rechargeable Batteries
 

Nickel/Cadmium Cells (NiCd):
These are one of the most common rechargeable battery types. Nickel Cadmium cells are found in battery packs for children's toys, cordless telephones, cordless screw-drivers, cordless drills, cordless vacuum cleaners and many other appliances. These cells use Cadmium plated nets for the anode and Nickel hydroxide Ni(OH)2 plated mesh for the cathode. Since the nickel content and cadmium content of these cells is minimal, they don't pose as severe of an environmental impact as other batteries, but just imagine an entire landfill full of these batteries (or any other battery for that matter)! Would you want to drink the water they contaminate? Do any of these look familiar? Perhaps in a cordless phone or electric shaver you may have?
 

The reaction for Nickel Cadmium batteries can be shown as:
Cd +NiO2 + 2H2O —> Cd(OH)2 + Ni(OH)2
 

Nickel/Metal Hydride (NiMH) Cells:
Becoming more and more popular, these batteries can are used for cellular phones, camcorders, power tools, laptops, and even electric vehicles. In modern NiMH batteries, the anode is made of many alloys, including Vanadium, Titanium, Zirconium, Nickel, Chromium, Cobalt, and even Iron. With the exception of the anode, these batteries are very similar in construction to the Nickel Cadmium cells.

THESE CAN BE RECHARGED OVER 1000 TIMES!!

The NiMH cell costs more and lasts half as long as the NiCd cell, but it has from 30-50% more capacity and does not suffer from the memory effect, like NiCd batteries. To avoid the memory effect, fully discharge the battery once every 25 charges.


 

The overall reaction for Nickel Metal Hydride cells can be given as:
NiOOH + MH —> Ni(OH)2 + M


Lithium Ion Cells:
Nearly every household has at least one appliance that uses a Lithium Ion battery. Do you have a cell phone or a laptop computer? If so, you probably have a Lithium Ion battery as well!

Some companies manufacture Lithium Ion button batteries! Remember the Mercuric Oxide button cells used in ties, hearing aids, and watches? More and more button batteries are lithium ion because of increasing environmental concern.

Well, sorry to say there's no chemistry for you here because the components in Lithium Ion batteries are so diverse (such as LiCoO2, NiNi0.3Co0.7O2, LiNiO2, LiV2O5, LiV6O13, LiMn4O9, LiMn2O4, LiNiO0.2CoO2 to name a few!) to list.
 

Rechargeable Alkaline Cells:
You remember the standard version of the alkaline battery, right? Well this is very close to it but with the added advantage of being rechargeable! The better-made batteries have a shelf life of roughly 4 years which means they can be charged and stored for 4 years without losing their charge!! Rechargeable Alkaline cells can be charged at higher ambient temperatures as well, so if you have a solar battery charger (which often times heats the batteries due to the sun), this may be the rechargeable battery for you!

These batteries pose a lesser environmental risk due to their components and long life. Often times these batteries can be recharged 1600 times or more!

 

The overall cell reaction can be expressed as:
Zn + 2MnO2 + H2O <==> ZnO + 2MnOOH

Environmental Impact of Batteries
 

Where do your old or used batteries go? Many new types are recyclable and can be turned back into useable raw materials. The unfortunate truth is that most types of batteries are not recycled because people don't know the difference. Most used batteries end up in a landfill, eventually leaking their contents, possibly contaminating ground water. Some are incinerated, possibly spewing heavy metals into the air.  So, be careful and look on the battery for the recycle symbol: don't just toss them...recycle all you can.  Most stores now accept batteries for recycling.

Alkaline cells pose a lesser risk to the environment because of their decreased heavy metal content, though they still contain some zinc and manganese. Alkaline cells are less reactive and a result, they take longer to leak, but they will invariably leak given time in a landfill. Again, the same concerns arise when heavy metals are involved and the same afflictions apply as in the Leclanché dry-cell.
 

Gaston Plante invented the lead-acid battery in 1859! Lead acid batteries are still one of the most widely used batteries, powering communications equipment, backup power systems, and even starting your car! Lead acid batteries are quite the success story not only in use, but in disposal!! About 93 percent of all lead acid batteries are recycled! Compare that to 44% of newspapers, 57% of aluminum cans, and 39% of plastic bottles; lead-acid batteries are among the most highly recycled consumer products!
 

Because of their zinc and manganese content, these batteries pose an environmental risk. Any heavy metals that leak out of the battery may get into the water supply. No matter how well sealed or well made the liner in a landfill, it will probably leak sometime and when it does, the toxins will be released into the environment. According to the US Center for Disease Control and Prevention, heavy metals are known to cause birth defects, cancer, and various mental disorders.
 

Though rechargeable, these batteries contain very toxic components. Contents such as LiCoO2, NiNi0.3Co0.7O2, LiNiO2, LiV2O5, LiV6O13, LiMn4O9, LiMn2O4, LiNiO0.2CoO2 just to name a few, will do very unpleasant things to the human body and the environment. Lithium Ion batteries contain nearly ALL of the most dangerous heavy metals! Their contents varies in quantity and chemical composition, but they do not contain mercury. This makes them less hazardous than Mercury Oxide cells, even though they may contain Vanadium, Chromium Cobalt, Nickel, and Manganese.
 

From the name, you may guess these are not very environmentally friendly. Mercury poisoning is quite serious and some times fatal. Mercury poisoning is many times misdiagnosed as a psychiatric disorder. Often, the patients are treated for a disorder they do not have, and die from the mercury poisoning before it is detected. Mercury poisoning is known to cause motor function disabilities, brain damage, kidney damage, speech and language impairments, central nervous system damage, and a plethora  of other afflictions.  If you have this type of battery, make sure it is properly recycled.
 

Since these batteries contain heavy metals, they pose the same risk as Leclanché and Alkaline cells. They have the advantage of being rechargeable, which means fewer of them are thrown away as compared to disposable cells. In fact, since they are rechargeable in excess of 1000 times, it would seem that 1/1000 as many are thrown away as the equivalent disposable battery!
 

The United States Environmental Protection Agency has an interesting view on universal waste. Universal waste is waste that is considered to have "limited environmental impact" and be "relatively harmless in nature" and is to be sent to landfills. As of yet, it is unclear as to which dictionary/lexicon they are using to define "harmless" since all of the above cells, with the exception of the Mercury Oxide cells, are considered Universal Waste!

 

So How Many Batteries Do We Use?

 

In the US alone, we use about 475 million batteries each year!! Of those batteries, 39% are zinc-carbon disposables, 2% are button cells, 51% are disposable alkaline, and only 8% are rechargeable!!

 
TOO MANY DISPOSABLES!!

In terms of weight in tons of batteries sold in the US each year, 47,000 tons are zinc carbon,  72,000 tons are disposable alkaline, 400 tons are button cells, 700 tons are disposable Lithium batteries, 13,000 tons are Nickel Cadmium rechargeables, 5,000 tons are Nickel Metal Hydride rechargeables, 15,000 tons are sealed lead acid, and 2,000 tons are rechargeable Lithium Ion batteries.

 
Last Updated ( Tuesday, 26 February 2008 )
 
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