My Knowledge Hub by Arabella Palatolon

palatolonarabella — 2025-01-03 21:54:28 UTC

A battery is a device that converts chemical energy contained within its active materials directly into electric energy by means of an electrochemical oxidation-reduction (redox) reaction. 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.

palatolonarabella — 2025-01-03 22:08:35 UTC

Batteries and similar devices accept, store, and release electricity on demand. Batteries use chemistry, in the form of chemical potential, to store energy, just like many other everyday energy sources. For example, logs and oxygen both store energy in their chemical bonds until burning converts some of that chemical energy to heat. Gasoline and oxygen mixtures have stored chemical potential energy until it is converted to mechanical energy in a car engine. Similarly, for batteries to work, electricity must be converted into a chemical potential form before it can be readily stored. Batteries consist of two electrical terminals called the cathode and the anode, separated by a chemical material called an electrolyte. To accept and release energy, a battery is coupled to an external circuit. Electrons move through the circuit, while simultaneously ions (atoms or molecules with an electric charge) move through the electrolyte. In a rechargeable battery, electrons and ions can move either direction through the circuit and electrolyte. When the electrons move from the cathode to the anode, they increase the chemical potential energy, thus charging the battery; when they move the other direction, they convert this chemical potential energy to electricity in the circuit and discharge the battery. During charging or discharging, the oppositely charged ions move inside the battery through the electrolyte to balance the charge of the electrons moving through the external circuit and produce a sustainable, rechargeable system. Once charged, the battery can be disconnected from the circuit to store the chemical potential energy for later use as electricity.

palatolonarabella — 2025-01-03 22:19:03 UTC

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palatolonarabella — 2025-01-03 22:39:01 UTC

Battery types

Batteries can be broadly divided into two major types.

Primary Cell / Primary battery
Secondary Cell / Secondary battery

Based on the application of the battery, they can be classified again. They are:

palatolonarabella — 2025-01-03 22:39:59 UTC

Household Batteries
These are the types of batteries which are more likely to be known to the common man. They find uses in a wide range of household appliances (such as torches, clocks, and cameras). These batteries can be further classified into two subcategories:
- Rechargeable batteries Nickel
  Examples: Cadmium batteries, Lithium-Ion
- Non-rechargeable batteries
  Examples: Silver oxide, Alkaline & carbon zinc
Industrial Batteries
These batteries are built to serve heavy-duty requirements. Some of their applications include railroad, backup power and more for big companies. Some examples are:
Nickel Iron
Wet Nickel Cadmium (NiCd)
Vehicle Batteries
These are more user-friendly and a less complicated version of the industrial batteries. They are specifically designed to power cars, motorcycles, boats & other vehicles. An important example of a vehicle battery is the lead-acid battery.

Primary cell/ Primary battery

palatolonarabella — 2025-01-03 22:59:22 UTC

These are batteries where the redox reactions proceed in only one direction. The reactants in these batteries are consumed after a certain period of time, rendering them dead. A primary battery cannot be used once the chemicals inside it are exhausted.

An example of a primary battery is the dry cell – the household battery that commonly used to power TV remotes, clocks, and other devices. In such cells, a zinc container acts as the anode and a carbon rod acts as the cathode. A powdered mixture of manganese dioxide and carbon is placed around the cathode. The space left in between the container and the rod are filled with a moist paste of ammonium chloride and zinc chloride.

The redox reaction that takes place in these cells is:

At Anode

Zn(s) –> Zn²⁺ (aq) + 2e^–

At Cathode

2e^–+ 2 NH₄⁺ (aq) –> 2 NH₃(g) + H₂ (g)

2 NH₃(g) +Zn²⁺ (aq) –> [Zn (NH₃)₂]²⁺ (aq)

H₂ (g) + 2 MnO₂ (S) –> Mn₂O₃ (S) + H₂O (l)

Thus, the overall cell equation is:

Zn(s) + 2 NH₄⁺ (aq) + 2 MnO₂ (S) –> [Zn(NH₃)₂]²⁺ (aq) + Mn₂O₃ (S) + H₂O (l)

Another example of the primary cell is the mercury cell, where a zinc-mercury amalgam is used as an anode and carbon is used as a cathode. A paste of HgO is used as an electrolyte. These cells are used only in devices that require a relatively low supply of electric current (such as hearing aids and watches).

Secondary cell/secondary battery

palatolonarabella — 2025-01-03 23:07:11 UTC

These are batteries that can be recharged after use by passing current through the electrodes in the opposite direction, i.e. from the negative terminal to the positive terminal.

For example, a lead storage battery that is used in automobiles and inverters can be recharged a limited number of times. The lead storage battery consists of a lead anode and the cathode is a lead grid packed with lead dioxide. Sulphuric acid with a concentration of 38% is used as an electrolyte. The oxidation and reduction reaction involved in this process are listed below.

At Anode

Pb –> Pb²⁺+ 2 e^–

Pb+ SO₄^2– –>PbSO₄(electrode) + 2 e^–

At Cathode

2 e^–+ PbO₂+ 4 H⁺ –> Pb²⁺+ 2 H₂O

2 e^–+ PbO₂+ 4 H⁺+ SO₄^2- –> PbSO₄(electrode) + 2 H₂O

In order to recharge these batteries, the charge is transferred in the opposite direction and the reaction is reversed, thus converting PbSO₄ back to Pb and PbO_2.

Another example of the secondary cell is the nickel-cadmium cell. These cells have high storage capacities and their lifespan is relatively long (compared to other secondary cells). However, they are difficult to manufacture and maintain.

palatolonarabella — 2025-01-03 23:11:38 UTC

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palatolonarabella — 2025-01-03 23:36:51 UTC

palatolonarabella — 2025-01-03 23:56:51 UTC

An appropriate reduction electrode and an oxidation electrode are combined to create a galvanic cell, which uses a redox process to transform chemical energy into electrical energy. Through a porous diaphragm or a salt bridge, two electrolytic solutions, in which electrodes are submerged, are connected to one another. A device that makes use of the electrical energy generated in the outer circuit is linked to the two electrodes.

palatolonarabella — 2025-01-03 23:59:06 UTC

At the oxidation electrode, oxidation takes place. A negative potential is produced by the accumulation of these electrons on the electrode. Due to the reduction process taking place there, a positive potential forms at the reduction electrode. Due to a difference in potential between these two electrodes when they are linked, electrons begin to flow from the oxidation electrode to the reduction electrode in the outer circuit. As a result, an electric current is generated.

The electrode where oxidation takes place is referred to as the anode, while the electrode where reduction occurs is referred to as the cathode. The cathode and anode in a galvanic cell each have a positive and negative polarity.

Parts of Galvanic Cell

palatolonarabella — 2025-01-04 00:01:29 UTC

Electrodes: a combined name given to anode and cathode where oxidation and reduction take place respectively.
Electrolyte: aqueous solution of compounds that help the movement of ions.
Salt bridge: A concentrated solution of an inert electrolyte is contained in a U-shaped tube known as a salt bridge. Examples of electrolytes are KC_l,KNO₃,K₂SO₄ etc., or solidified solution of such an electrolyte in Agar-Agar and gelatin. These inert electrolytes do not take part in the reduction reaction. The function of the salt bridge is to allow the movement of ions from one solution to the other without mixing two solutions. Thus, electron flow in the outer circuit in the wire and the inner circuit are completed by the flow of ions from one cell to the other through the salt bridge. The salt bridge maintains the electrical neutrality of the solution in the two half-cells.
Voltmeter: A device used to measure voltage in the closed circuit.

Uses of Galvanic Cell

palatolonarabella — 2025-01-04 00:02:52 UTC

They are commonly used as a source of electrical power, such as in batteries.
They can also be used in electroplating, where one metal is coated with another metal using an electric current.
Galvanic cells are used in certain types of medical devices, such as heart pacemakers.
They are also used in water treatment systems to control the acidity of water.

palatolonarabella — 2025-01-04 00:06:44 UTC