What is a Battery?
A battery can be defined as an electrochemical device (consisting of one or more electrochemical cells) which can be charged with an electric current and discharged whenever required. Batteries are usually devices that are made up of multiple electrochemical cells that are connected to external inputs and outputs. Batteries are widely employed in order to power small electric devices such as mobile phones, remotes, and flashlights. Historically, the ‘term’ battery has always been used in order to refer to the combination of two or more electrochemical cells. However, the modern definition of the term ‘battery’ is believed to accommodate devices that only feature a single cell.
Batteries are broadly classified into two categories, namely primary batteries and secondary batteries. Primary batteries can only be charged once. When these batteries are completely discharged, they become useless and must be discarded. The most common reason why primary batteries cannot be recharged is that the electrochemical reaction that takes place inside of them is irreversible in nature. It is important to note that primary batteries are also referred to as use-and-throw batteries.
On the other hand, secondary batteries are the batteries than can be charged and reused for many charging-discharging cycles. The electrochemical reactions that take place inside these batteries are usually reversible in nature. Therefore, secondary batteries are also known as rechargeable batteries. When discharging, the reactants combine to form products, resulting in the flow of electricity. When charging, the flow of electrons into the battery facilitates the reverse reaction, in which the products react to form the reactants.
Important Examples of Batteries
The Lead-Acid Battery
The lead-acid battery is believed to have been invented by the French physicist and inventor Gaston Planté in the year 1859. It is known to be one of the earliest rechargeable batteries. Despite the fact that the lead-acid battery has a very high energy-to-volume ratio and also a very low energy-to-weight ratio, the electrochemical cells in this battery are known to have a fairly large power-to-weight ratio. This can be attributed to their ability to produce strong surge currents. These features of the lead-acid battery, along with its relatively low cost, makes it highly desirable for use in motor vehicles and automobiles in order to provide the high current required to start the engine.
Some key characteristics of the lead-acid battery are:
- It has the ability to hold an electric charge for up to 3 years.
- It is ideal for use as an emergency power backup.
- It is one of the most inexpensive batteries in its output range.
The Nickel-Cadmium Battery (also known as the NiCad Battery)
The nickel-cadmium battery (sometimes referred to as the ‘NiCad’ battery) is a type of rechargeable battery that employs metallic cadmium and nickel oxide hydroxide as the electrodes o the battery. The NiCad battery is known to offer varying discharge rates that are dependent on the size of the battery itself. For example, the discharge rate (maximum) for a typical AA sized cell is approximately equal to 1.8 amperes. On the other hand, the discharge rate for a D size battery can be as high as 3.5 amperes.
The key features of the NiCad battery are listed below.
- The nickel-cadmium battery features a very fast and even discharge of electrical energy.
- This type of battery is widely available and is also known to be relatively inexpensive.
- The NiCad battery can most commonly be found in certain toys and small electronic devices such as TV remotes.
The Lithium-Ion Battery (also known as the LIB Battery)
The lithium-ion battery, often abbreviated to LIB, is a type of secondary battery which is rechargeable. LIBs are known to have many applications in powering electric vehicles and is also known to be used extensively in the aerospace industry.
Within the batteries, during the discharging process, lithium ions are known to pass from the negative electrode to the positive electrode (through an electrolyte ). These lithium ions are also known to travel back when charging. Lithium-ion batteries usually employ an intercalated lithium compound in the positive electrode and usually graphite in the negative electrode as the fuel. Lithium-ion batteries are highly desirable due to their high energy capacity, no memory effect (with the exception of LFP cells), and low self-discharge.
Some key characteristics of LIBs are listed below.
- The lithium-ion battery is regarded to be one of the most stable and safe batteries. This battery is also known to have a very high energy capacity.
- LIBs are widely used in mobile phones and portable computers (such as laptops and tablets).
- This battery has a very slow self-discharge. Furthermore, it is known to have twice the energy capacity of the NiCad battery.
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Frequently Asked Questions on Battery Definition
What is the Difference Between Primary Batteries and Secondary Batteries?
Primary batteries are the batteries in which the cell reactions are non-reversible in nature. Therefore, these batteries cannot be recharged. Once they are completely discharged, primary batteries must be thrown away. Secondary batteries, on the other hand, are known to feature reversible cell reactions. Therefore, the reactants in these batteries can be regenerated by supplying an electric current to it. Thus, secondary batteries can be reused over multiple charging and discharging cycles.
What are Wet Cell Batteries?
Wet cell batteries are electric batteries that contain liquid electrolytes. They are also known as vented cells and flooded cells. They are known to be used as learning tools in many electrochemistry labs. It is important to note that both primary and secondary cells can be constructed from electrolytes in the liquid state. Therefore, a wet cell need not necessarily be a primary cell.
What are Dry Cells?
A dry cell is an electrochemical cell in which the electrolyte is a paste. The electrolytes in such cells only contain enough moisture to facilitate the flow of current. Therefore, these cells can be operated in a wide range of orientations without the fear of spillage. Dry cells are widely used in portable electronic devices since they do not contain any free liquid.
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