The name “battery” is referred to a device that is composed of multiple cells, but it can be of a single cell. It is electric power source that consists of one or more electrochemical cells with external points for connections to supply electrical current to power devices such as flashlights, mobile phones, and electric cars. It stores and converts chemical energy to electrical energy. The whole process involves the flow of electrons from one electrode to another. This process is been controlled through an external circuit. The electron flow makes a usable electric current happen for work.
In a battery there are two terminals .The positive terminal is called the cathode and its negative terminal is the anode. The anode is the source of electrons that flows through the external electric circuit to the cathode terminal. A redox reaction converts the high-energy reactants to lower-energy products when the battery is connected to an external electric load .The free-energy difference, called the electric current then delivered to the external circuit.
Single-use or “disposable” has electrodes that is made of materials the changes irreversibly during discharge batteries.
For chargeable batteries the composition of the electrodes can be restored by reverse current method and thus can be discharged and recharged multiple times after applied current.
Different types of batteries:
Lithium ion batteries:
These are very popular and are being used for aircraft, electronic devices, satellites etc. These are lightweight and charge rapidly. These batteries last longer, but are good for long run.
Here the anode and the cathode serve as a host for the lithium ion. These ions move from the anode to the cathode during discharging process .In this process these ions are being inserted into voids in the crystallographic structure of the cathode. During charging the ions reverses the direction during charging process. There are no free lithium molecules within a lithium-ion cell, as they are intercalated into host materials during charging or discharging process. Here the alternating layers of anode and cathode are being separated by a porous film, called separator.
Lead acid batteries:
These are large and heavy batteries being used for different kinds of equipment. It takes a lot of time to charge, but are affordable option.
Nickel cadmium batteries:
Nickel cadmium batteries are reliable and heavy duty batteries. These are difficult to maintain than other types of batteries. It consists of nickel hydroxide (NiOOH) in the cathode and cadmium (Cd) in the anode and here the electrolyte is potassium hydroxide (KOH). It has very low internal resistance as well as very good current conducting properties. It can supply extremely high currents and the recharging process is fast. These cells require a safety valve for a long service life.
Nickel metal hydride batteries:
Here the nickel hydroxide (NiOOH) is used in the cathode and a hydrogen storing metal alloy (MH) is used in the anode and potassium hydroxide (KOH) is being used for electrolyte. It has a higher energy density per volume and weight compared to the prior one.
Small sealed lead acid batteries:
These do not require addition of water to the cells. It vents less gas than wet lead-acid batteries .SSLA batteries are sometimes referred to as “maintenance free” batteries. It can be used in confined or poorly ventilated spaces. These batteries include a safety pressure relief valve.
There are two types of VRLA batteries:
Absorbed glass mat (AGM) battery:
It has the electrolyte that is absorbed in a fiber-glass mat separator.
Gel battery (“gel cell”):
It has the electrolyte that is mixed with silica dust that forms an immobilized gel.
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