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Batteries function principles and construction

2014-11-11 10:15  
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One of the most important and remarkable discoveries was electricity. The practical use of electricity has only been at our disposal since the mid-to late 1800s . The first method of generating electricity was by creating a static charge. In 1660 Otto von Guericke constructed the first electrical machine that consisted of a large sulphur globe which, when rubbed and turned, attracted feathers and small pieces of paper. Guericke was able to prove that the sparks generated were truly electrical.

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The first suggested use of static electricity was the  “electric pistol” invented by Alessandro Volta (1745-1827) an electrical wire was placed in a jar filled with methane gas. By sending an electrical spark through the wire, the jar would explode. In 1800 Volta discovered that a continuous flow of electrical force was generated when using certain fluids as conductors to promote a chemical reaction between the metals or electrodes.

Volta discovered further that the voltage would increase when voltaic cells were stacked on top of each other.

The first electric battery for mass production was designed in 1802 by Dr. William Cruickshank which arranged square sheets of copper soldered at their ends  together with sheets of zinc of equal size. These sheets were placed into a rectangular wooden box that was sealed with cement. The box was then filled with an electrolyte of brine, or watered down acid.

The evolution of the batteries and electricity since 1600 to 1999 is :

1600 Gilbert (England) Establishment electrochemistry study

1791 Galvani (Italy) Discovery of ‘animal electricity’

1800 Volta (Italy) Invention of the voltaic cell

1802 Cruickshank (England) First electric battery capable of mass production

1820 Ampère (France) Electricity through magnetism

1833 Faraday (England) Announcement of Faraday’s Law

1836 Daniell (England) Invention of the Daniell cell

1859 Planté (France) Invention of the lead acid battery

1868 Leclanché (France) Invention of the Leclanché cell

1888 Gassner (USA) Completion of the dry cell

1899 Jungner (Sweden) Invention of the nickel-cadmium battery

1901 Edison (USA) Invention of the nickel-iron battery

1932 Shlecht & Ackermann (Germany) Invention of the sintered pole plate

1947 Neumann (France) Successfully sealing the nickel-cadmium battery

Mid 1960 Union Carbide (USA) Development of primary alkaline battery

Mid 1970 Development of valve regulated lead acid battery

1990 Commercialization nickel-metal hydride battery

1992 Kordesch (Canada) Commercialization reusable alkaline battery

1999 Commercialization lithium-ion polymer

 

In our days are many different types of batteries but the basic principles for all of them is the same corrosion which is a chemical reaction which  involves removal of metallic electrons from metals and the formation of more stable compounds such as iron oxide in which the free electrons are usually less numerous.

Main types of batteries are :

Nickel Cadmium (NiCd) — mature and well understood but relatively low in energy density. The NiCd is used where long life, high discharge rate and economical price are important.

Main applications are two-way radios, biomedical equipment, professional video cameras and power tools. The NiCd contains toxic metals and is not environmentally friendly.

Nickel-Metal Hydride (NiMH) — has a higher energy density compared to the NiCd at the expense of reduced cycle life. NiMH contains no toxic metals. Applications include mobile phones and laptop computers.

Lead Acid — most economical for larger power applications where weight is of little concern. The lead acid battery is the preferred choice for hospital equipment, wheelchairs, emergency lighting and UPS systems.

Lithium Ion (Li-ion) — fastest growing battery system. Li-ion is used where high-energy density and light weight is of prime importance. The Li-ion is more expensive than other systems and must follow strict guidelines to assure safety. Applications include notebook computers and cellular phones.

Lithium Ion Polymer (Li-ion polymer) — a potentially lower cost version of the Li-ion. This chemistry is similar to the Li-ion in terms of energy density. It enables very slim geometry and allows simplified packaging. Main applications are mobile phones.

Reusable Alkaline — replaces disposable household batteries; suitable for low-power applications. Its limited cycle life is compensated by low self-discharge, making this battery

ideal for portable entertainment devices and flashlights.

Cells can be connected in series, positive to negative etc, to increase the output voltage.

It is not common for batteries or cells to be connected in parallel though it can be done to increase the current capacity.

How to make a home made battery

So we know how the batteries works let’s try to make a battery . To demonstrate the principle of batteries we need some materials : electrolyte, electrodes , support for electrodes and electrolyte .

We need vinegar ,salt and water for electrolyte , aluminium or zinc  and cooper ( foil ) plates for electrodes and one glass . First we need to make the electrolyte dissolving in a glass of water (200 ml) 25g of salt and 50 -80ml of vinegar.

If we use zinc and cooper electrodes the voltage will be high than if we will use cooper and aluminium .

After the sodium carbonate and salt are dissolved we need to mount the electrodes by hanging in the glass aluminium foil with a width of about 1 cm and about 5 cm long . In the opposite side of the glass we need to mount the other electrode ( cooper foil )  .

Make sure that the copper and aluminium do not touch each other, otherwise our battery becomes short-circuited.

The battery is now finished , the copper is the positive terminal and the aluminium is the negative terminal. Now we can measure the voltage between these two electrodes to see the voltage of the cell .

For testing the battery we need to make another cell and put together with the first cell and connect a LED or lamp between the electrodes .

After the battery has been used for a while you will notice that the copper is nice and clean. Using this home-made battery is therefore eminently suitable for the cleaning of copper or silver.

Even we have enough voltage to drive a lamp or LED , maybe they will not flash because we don’t have enough current , so we need to increase the capacity of the battery or we need to use a device with very small current  .