Electrical Storage: Present, Past, and Future

Present

There are six common types of rechargeable batteries:

  • Lead Acid.
  • Lithium Ion.
  • Lithium Ion Polymer.
  • Nickel Cadmium.
  • Nickel Metal Hydride.
  • Reusable Alkaline.

Of these six types, only Nickel Cadmium, Nickel metal hydride, and reusable alkaline are typically found as replacements for AAA, AA, C, D, and 9 volt batteries. In California, all batteries, both rechargeable and disposable, are considered to be hazardous waste when they are no longer useable. See more information on battery recycling and disposal.

Lead Acid–The acid in some lead acid batteries is a liquid, as is the case with automobile batteries. In other lead acid batteries the acid is in the form of a gel. Some of the typical uses for lead acid gel batteries are, wheel chairs, hospital equipment, emergency lighting, computer power backup, and building burglar alarm backup.

Lithium Ion–Lithium ion batteries can store much more energy for their mass than most other types of batteries. Lithium is the lightest of all metals and is the third lightest element after Hydrogen and Helium. Lithium ion batteries are more expensive than other types. Typical applications include notebook computers and cellular phones.

Lithium Ion Polymer (Lithium Polymer)–Lithium ion polymer batteries have similar energy for their mass as Lithium ion batteries, but at potentially lower cost. The possible applications of Lithium polymer batteries are similar to those of Lithium ion batteries. The technology of Lithium polymer batteries is very new and still evolving.

Nickel Cadmium (NiCd)–NiCd technology is mature and well understood. However NiCd batteries store relatively less energy than Lithium ion and Lithium ion polymer batteries. NiCd batteries are used where long life, high discharge rate, and low price are important. See Rechargeable Batteries and Changers for more details.

Nickel-Metal Hydride (NiMH)–NiMH batteries store somewhat more energy than NiCd, but for a shorter period of time. See Rechargeable Batteries and Changers for more details.

Low Self Discharge (LSD)–A new type of NiMH battery readily available in AAA and AA sizes. C and D sizes are hard to find. LSDs are different than other rechargeable AAA and AA batteries because they lose significantly less charge when not in use. According to manufacturers, they lose only 15 percent per year, compared to 4 percent per day for ordinary NiMH. See Rechargeable Batteries Compared. LSD batteries can be charged with ordinary NiMH chargers.

Reusable Alkaline–Reusable alkaline batteries provide fewer charge/discharge cycles than any other rechargeable battery. However, they hold their charge longer than some types. Typical uses include portable radios, portable entertainment devices, and flashlights.

Past and Future

There are two ways to store electrical energy, chemically and statically.

Batteries are a means of chemical storage. Electrons that are a part of the molecules of the chemicals or substances in a battery are coaxed to leave those chemicals or substances and become a part of the electrical current that we use. In virtually all batteries the process is reversible to some extent. If electrons are returned to the chemicals or substances in a battery, the electrons can again be used as electrical current. In disposable batteries the process cannot be reversed very well, and in most cases, it is either impractical or unsafe to do so. In reusable or rechargeable batteries, the process can be more readily reversed with a battery charger. Battery chargers return electrons to the chemicals or substances in batteries. In the case of most batteries sold as rechargeable, the process can be reversed very well, but not perfectly. Even with the best of care, after a number of years rechargeable batteries become unusable.

In the year 1800 an Italian named Alessandro Volta developed the first battery that produced a reliable, steady current of electricity. He used alternating discs of zinc, copper, and pieces of cardboard soaked in brine. It is from Alessandro Volta that the electrical term “Volt” was derived.

Before there were batteries, it was known that electricity could be stored statically. Experimenters learned that an electrical charge could be stored between two sheets of metal that were positioned close to each other. This sort of device has taken many forms over the years, and has had several names. It was first invented by Ewald Georg von Kleist in 1745, and was known as a Leyden Jar. This and other forms of the device later became known as condensers because electricity was incorrectly imagined by some experimenters to be a type of liquid that could be condensed, as water or alcohol can be condensed with a still. The device later became known as the capacitor, a term that is used today.

Capacitors have other uses besides storing electricity, and most capacitors that are used to store electricity are not used as a battery.

The historical problem with using a capacitor as a source for electrical energy has been that the static electricity in the capacitor could only be used all at once in one short powerful shock. There was no way to release electrons from a capacitor very slowly and gradually as a battery releases them, until recently.

Technology today allows the electrons in small capacitors to be released slowly and gradually in a manner similar to the way a battery releases electrons. A few wristwatches and flashlights are now powered in this way. They use capacitors, not batteries. (See Alternative Power Products.)

Today’s technology might soon make practical other means to store and release electrons. Electrical storage technology and nanotechnology seem to be on merging paths. Nanotechnology is a catch-all description of activities that deal with extremely small structures and objects with dimensions generally in the range of 0.1 nanometers to 100 nanometers. One nanometer (nm) is one billionth of a meter. An hydrogen atom has a diameter of about 1/10 nm. An human hair is about 75,000 nm in diameter.

Carbon nanotubes (CN) are cylinders of carbon atoms that are 1 or 2 nanometers in diameter. The molecular structure of the carbon atoms resembles wire mesh with six sided holes, similar to chicken wire. A carbon nanotube resembles an extremely tiny seamless tube of chicken wire. Carbon nanotubes have at least two potential uses. They can serve as tiny wires due to a property called electron tunneling, which lets them propagate electrical signals at scales where ordinary current flow is impossible. Carbon nanotubes can also store electrical energy.

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For more information contact: Office of Public Affairs, opa@calrecycle.ca.gov