Batteries
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[edit] Overview
The term "battery" is a generic term for an elctro-chemical energy storage device.
The basis of all batteries is the electrochemical cell.
Technically, a "battery" is a series of cells connected in series to create higher voltages than a single cell can provide (this term likely originates from artillery - an artillery battery is a group of guns). Most "batteries" are really cells.
[edit] Rechargeable
Rechargable cells are deigned to be recharged - typically hundreds of times - once drained.
Rechargables typically cost more on a per-cell basis than primary cells, but the energy cost of charing them is usually negligible, so rechargable cells end up being much more economical than primaries in the long run.
[edit] Lead-Acid
Lead-Acid is the oldest rechargable cell chemistry. The lead-acid cell was invented in 1859 by French physician Gaston Planté©.
Lead-Acid cells are typically very bulky, with an energy density much lower than other chemistries, but they excel in high-drain applications where size and weight are not major issues.
Lead-Acid cells are typically available in almost any size larger than typical "household" sizes.
They are sensitive to being overdischarge, or stored without being charged, but have the advantage of being less damaged to being overcharged.
[edit] Nickel-Cadmium
(NiCd)
NiCd is a "mature" rechargable chemistry. It was invented in 1899 by Waldmar Jungner of Sweden, but practical applications did not arise until the 1930s, with sealed units becoming available in 1947.
NiCd excells at high-drain applications. Despite the availability of newer, higher-density chemistries such as NiMH, Lithium-ion, and Lithium-Polymer, NiCd is the chemistry of choice for high-drain applications such as power tools, 2-way radios, and medical equipment.
NiCd cells are readily available in the "household" sizes common to Alkaline cells.
[edit] Nickel-Metal Hydride
(NiMH)
NiMH is a relative newcomer to the rechargable cell field. Research on nickel-metal hydrides began in the 1970s, with the chemistry seeing industrial applications in the 1980s and cells reaching consumers in the late 1990s.
NiMH is excellent for "everyday" applications as an alkaline replacement. It does not mind partial charge or discharge cycles. Its energy density is greater than that of NiCd.
NiMH cells are readily available in the "household" sizes common to Alkaline cells.
[edit] Rechargable Alkaline
Rechargable alkaline is newer than NiCd, but older than NiMH. As the name implies, it is a variant on Alkaline chemistry that can be recharged.
Rechargable alkaline cells have rather limited use. Their cycle life is very limited - typically 25-100 charge/discharge cycles. Although conventional rechargable economics apply, the cost of special chargers and low cycle life limits their appeal. The one advantage that they have over other rechargables is their low self-discharge rate - resulting in a long shelf life.
Rechargable alkaline cells are readily available in the "household" sizes common to Alkaline cells.
[edit] Lithium-Ion
(Li-ion)
Lithium-ion is a relative newcomer to consumer electronics - the first commercial li-ion cell was offered by Sony in 1991.
Li-ion offers greater energy density than NiMH and NiCd, weighs less, and requires less maintenance. Li-ion is rapidly becoming the chemistry of choice for compact portable electronics due to its slim size and high energy density.
Li-ion cells are available in some "household" sizes as well as a number of standard industrial sizes. Rarely are "bare" li-ion cells sold to the public because of their increased voltage, specialized charging and maintenance requirements.
[edit] Lithium-Polymer
(Li-poly)
Lithium-polymer is closely related to the Li-ion. Its mass-market debut was close to that of the li-ion.
Li-poly is unique in that it uses a dry solid polymer electrolyte. This allows the cell to be as thin as 1mm. In production cells, some gelled electrolyte is present to enhance conductivity between the 2 layers of polymer. Li-poly is used primarily in applications where small, thin cells are required.
There are no standard sizes for li-poly cells. They are designed for special applications and not made available to the general public for the same reasons as li-ion.
[edit] Non-rechargeable
Non-rechargable cells - also known as "primary cells" - are designed to be used once and disposed of once they can no longer provide energy.
[edit] Carbon-Zinc
Carbon-Zinc is the oldest primary chemistry - invented in 1800 by Alessandro Volta. The modern carbon-zinc cell is a descendent of Volta's "wet cell," with the first "dry cells" seeing production in the 1880s.
Carbon-zinc cells (also known as "Heavy-Duty" and "Super Heavy-Duty") have the lowest energy density and shortest shelf life amongst primary cells. They are still available because they are cheaper to make than Alkaline cells, and weight less.
Carbon-zinc cells are readily available in the "household" sizes common to Alkaline cells.
[edit] Alkaline
The alkaline chemistry is similar to Carbon-Zinc, but more potent. The technical term for this chemistry is "alkaline-manganese" (hereafter referred to as "alkaline"). Alkaline become commonly available to consumers starting in the 1950s.
Alkaline cells are good for "every day" applications. They offer better-than average energy density and shelf lives approaching 10 years.
Alkaline cells are available in "household" sizes.
[edit] Lithium
Lithium primary cells became available in the 1970s.
Lithium offers the highest energy density of all chemistries. Lithium primary cells are commonly used for high-end electronics such as high-performance flashlights, cameras, and military equipment; not surprisingly, lithium cells typically cost much more than all other chemistries. Lithium cells also have exceptional shelf lives - typically quoted as 10-20 years.
There are 4 common lithium primary chemistries:
- Lithium/Iron Disulfide - 1.7V/cell (Energizer AA and AAA cells)
- Lithium/Manganese Dioxide - 3V/cell (CR123A, CR2 cells, "CR" coin cells)
- Lithium/CFx - 2.8V/cell ("BR" coin cells)
- Lithium/Thionyl Chloride - 3.6V/cell (SAFT cells)
[edit] Mercury
Mercury cells were invented in the late 1930s by Samuel Ruben.
Mercury was a popular chemistry due to its relatively stable voltage throughout its operating life. There are many older electronics that used a mercury cell for voltage reference.
Mercury cells are no longer readily available, due to concerns about safe disposal to avoide mercury contamination. They were usually limited to "coin cell" sizes.
[edit] Supercapacitors
Supercapacitors (supercaps) are essentially high-capacity capacitors. They are sometimes referred to as "BFC's" (Big F---ing Capacitors).
Supercaps have substantially lower energy densities than electro-chemical batteries, but can be charged and discharged at substantially greater rates. Supercaps could potentially be used in place of batteries for short runtime or low-discharge applications.
Supercapacitors are reltively new. Their capacities are expected to increase dramatically as the technology matures. Whether they will be able to compete with conventional batteries has yet to be determined.
[edit] Fuel cells
Fuel cells use catalysis to separate the protons and electrons in the reactant fuel. The electrons are forced to flow through a circuit, which how the electrical power is produced.
[edit] External Links
Wikipedia: Battery (electricity)
