Categories and types of batteries
Batteries are classified into two broad categories:
Primary batteries irreversibly transform chemical energy to electrical energy. When the initial supply of reactants is exhausted, energy cannot be readily restored to the battery by electrical means.
Secondary batteries can be recharged; that is, they can have their chemical reactions reversed by supplying electrical energy to the cell, restoring their original composition. Secondary batteries are not indefinitely rechargeable due to ageing mechanisms.
These are most commonly used in portable devices that have low current drain, are used only intermittently, or are used well away from an alternative power source, such as in alarm and communication circuits where other electric power is only intermittently available. Disposable primary cells cannot be reliably recharged, since the chemical reactions are not easily reversible and active materials may not return to their original forms. Battery manufacturers recommend against attempting to recharge primary cells.
Common types of disposable batteries include zinc–carbon batteries and alkaline batteries. In general, these have higher energy densities than rechargeable batteries, but disposable batteries do not fare well under high-drain applications with loads under 75 ohms (75 Ω). Professional type of primary batteries are the lithium-manganese ( Li-MnO2),
Secondary batteries, also known as secondary cells, or rechargeable batteries, must be charged before use;
The oldest form of rechargeable battery is the lead–acid battery.
Other rechargeable batteries include nickel–cadmium (NiCd), nickel metal hydride (NiMH), and lithium-ion (Li-ion) cells. More recently have been developped molten-salt batteries such as sodium–sulfur battery (or NaS battery) and sodium-nickel chloride (Na-NiCl2).
Many other type of batteries have been studied or are currently under development, but have not achieved large commercial volumes.
Nickel cadmium cell (NiCd)
The active components of a rechargeable NiCd battery in the charged state consist of nickel hydroxide (NiOOH) in the positive electrode and cadmium (Cd) in the negative electrode. For the electrolyte, usually caustic potash solution is used.
Nickel metal hydride cell (NiMH)
The active components of a rechargeable NiMH battery in the charged state consist of nickel hydroxide (NiOOH) in the positive electrode and a hydrogen storing metal alloy (MH) in the negative electrode as well as an alkaline electrolyte.
Lithium ion cell (LiIon/Li polymer)
The active components of a rechargeable lithium ion battery in the charged state consist of lithium dioxide in the positive electrode and graphite in the negative electrode. LiIon cells attain, when fully charged, a voltage of approximately 4.2 V.
In addition to the main advanced rechargeable batteries technologies (Li-Ion, Ni-MH, Ni-Cd), the lead acid technology has been used for a long time to build rechargeable batteries. Their typical application is the automotive industry for starting-lighting-ignition (sli), and back-up energy storage. Recently, new technologies are emerging, such has sodium sulfur Na-S, or sodium-nickel chloride Na-NiCl2 (Zebra).