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d) Lithium Cells

Anode: Li
Cathode: Various liquid or solid materials
Electrolyte: SOCl2, SO2Cl2, or organic solutions

Lithium batteries consist of a lithium anode, which is an organic electrolyte that conducts the current, and a cathode. Lithium cobalt oxide, a material from which lithium can be easily removed, is the most common cathode compound. When the battery is charged, lithium ions are driven from the cathode into the anode; when the charge is removed, the lithium flows back to the cathode.

While there are many styles of lithium primary batteries, they all provide long-term storage life at room temperature and long operational life over a wide range of operating temperatures.

Common types of primary lithium batteries include: lithium / sulfur dioxide (Li/SO2), lithium / thionyl chloride (Li/SOCl2), lithium / manganese dioxide (LiMnO2), lithium / carbon monofluoride (Li/(CF)n), lithium / copper oxide (LI/CuO), and lithium / iodine (LiI2), and lithium anode reserve batteries (including lithium / vanadium pentoxide, lithium / thionyl chloride, and lithium / sulfur dioxide styles).

Standard battery types include: AAAA, AAA, N, 1/3 AA, 2/3 AA, AA, 1/2 A, 2/3 A, A, 4/5 Cs, Cs, C, 1/2 D, D. Each of these styles is cylindrical, with positive top that has an extended terminal, and a negative slightly indented bottom. 9-volt (9V) batteries are also a standard type, but they are rectangular with extended positive and negative terminals on their tops.

There are three main types of lithium battery, below is a overview of the different types:

Manganese Dioxide Lithium Battery

These are mainly used in the coin type batteries often known as watch batteries or button cells (CR). They are small and lightweight with an operating voltage of 3V and the ability to operate over a wide temperature range. They have a wide range of applications, i.e. watches, calculators and memory backup. They are prefered in these devices due to their stable discharge characteristics through low internal resistance and high operating voltage. As with all lithium batteries they have superior leakage resistance and excellent storage characteristics.

Thionyl Chloride Lithium Battery

These batteries are totally constructed of inorganic materials. This allows it to be used much longer than conventional batteries, which contain organic compounds in some locations. This battery is ideal for such long-term applications as power for electronic devices and electric power, water and gas meters and especially as a backup power source for memory ICs.

Manganese Dioxibe Lithium Battery

These are normally coin type small, lightweight rechargeable batteries. This battery employs specially treated manganese dioxide for the positive material and a lithium-aluminium compound for the negative material.

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e) Mercury Oxide Cells

Anode: Zinc (or cadmium)
Cathode: Mercuric Oxide (HgO)
Electrolyte: Potassium hydroxide

This is an obsolete technology. Most if not all of the manufacture of these cells has been stopped by government regulators. Mercury batteries come in two main varieties: zinc/mercuric oxide and cadmium/mercuric oxide. The zinc/mercuric oxide system has high volumetric specific energy (400 Wh/L), long storage life, and stable voltage. The cadmium/mercuric oxide system has good high temperature and good low temperature (-55 C to +80 C, some designs to +180 C) and has very low gas evolution.

Zn + HgO = ZnO + Hg E = 1.35 V
Cd + HgO + H2O = Cd(OH2) + Hg E = 0.91
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f) Zinc/Air Cells
Anode: Zn
Cathode: Oxygen (O2)
Electrolyte: Potassium hydroxide (KOH)

The zinc air cell fits into the alkaline cell category because of its electrolyte. It also acts as a partial fuel cell because it uses the O2 from air as the cathode. Oxygen is let in to the cathode through a hole in the battery and is reduced on a carbon surface.

A number of battery chemistries involve a metal oxide and zinc. The metal oxide reduces, the zinc becomes oxidized, and electric current results.

Half-reactions:

Zn + 2OH- -> Zn(OH)2
1/2 O2 + H2O + 2e -> 2 OH-

Overall reaction:
2Zn +O2 +2H2O -> 2Zn(OH)2 E=1.65 V

The electrolyte is an alkali hydroxide in 20-40% weight solution with water. One disadvantage is that since these hydroxides are hygroscopic, they will pick up or lose water from the air depending on the humidity. Both too little and too much humidity reduces the life of the cell. Selective membranes can help. Oxygen from the air dissolves in the electrolyte through a porous, hydrophobic electrode-a carbon-polymer or metal-polymer composite.

This cell has the additional benefits of being environmentally friendly at a relatively low cost.

These batteries can last indefinitely before they are activated by exposing them to air, after which they have a short shelf life.