Principle of Electrolysis
Faraday Laws of Electrolysis
Applications of Electrolysis
Working of Lead Acid Battery
Nickel Iron Batteries or Edison Batteries
Aluminum Air Battery
Series Parallel Battery Cells
In the modern era, electrical energy is normally converted from mechanical energy, solar energy, and chemical energy, etc. A battery is a device that converts chemical energy to electrical energy. The first battery was developed by Alessandro Volta in the year of 1800. In the year 1836, John Frederic Daniell, a British chemist developed the Daniell cell as an improved version of the voltaic cell. From that time until today the battery has been the most popular source of electricity in many daily life applications.
In our daily life we generally use two types of batteries, one of which is the use and through type meaning it can be used once before it totally discharges. Another type of battery is rechargeable which means it can be reused multiple times by recharging it externally. The former is called primary battery and the latter is called secondary battery.
Batteries can be found in different sizes. A battery may be as small as a shirt button or may be so big in size that a whole room is required to install a battery bank. With this variation of sizes, the battery is used anywhere from small wrist watches to a large ship.
We often see this symbol in many diagrams of electrical and electronics network. This is the most popularly used symbol for battery. The bigger lines represent positive terminal of the cells and smaller lines represent negative terminal of the cells connected in the battery.
We are often confused about the terms battery cell and battery. We generally to refer a battery as a single electrochemical cell. But literally, battery does not mean that. Battery means a number of electrochemical cells connected together to meet a certain voltage and electric current level. Although there may a single cell battery, literally, battery and cell are different.
History of BatteryIn the year of 1936 during the middle of summer, an ancient tomb was discovered during construction of a new railway line near Bagdad city in Iraq. The relics found in that tomb were about 2000 years old. Among these relics there were some clay jars or vessels which were sealed at the top with pitch. An iron rod, surrounded by a cylindrical tube made of wrapped copper sheet was projected out from this sealed top. When these pots were filled with an acidic liquid, they produced a potential difference of around 2 volts between the iron and copper. These clay jars are suspected to be 2000 year old battery cells.
In 1786, Luigi Galvani, an Italian anatomist and physiologist, was surprised to see that when he touched a dead frog’s leg with two different metals the muscles of the legs would contract. He could not understand the actual reason why, otherwise he would have been known as the first inventor of the battery cell. He thought the reaction might be due to a property of the tissues. After that, Alessandro Volta realized that same phenomenon could be created by using cardboard soaked in salt water instead of frog's leg. He sandwiched a copper disc and a zinc disc with a piece of cardboard soaked in salt water in between them and found a potential difference between the copper and zinc. After that in 1800, he developed the first Voltaic Pile (battery) constructed of alternating copper and zinc discs with pieces of cardboard soaked in brine between them. This system could produce measurable electrical current. Alessandro Volta's voltaic pile was considered the first "wet battery cell". Thus, the history of battery began.
The main problem with the Voltaic pile was that it could not deliver current for a long time. This problem was solved by a British inventor John F. Daniell in 1836. He invented a more developed version of the battery cell which is known as the Daniell cell. Here in this cell, one zinc rod is immersed in zinc sulfate in one container and one copper rod is immersed in copper (II) sulfate in another container. The solutions of these two containers are bridged by a U shaped salt bridge. A Daniell cell could produce 1.1 volt and this type of battery lasted much longer than the Voltaic pile.
In 1839, the fuel cell was designed by Sir William Robert Grove, a discoverer and man of science. He mixed hydrogen and oxygen within an electrolyte solution, and created electricity and water. The fuel cell did not deliver enough electricity, but it is helpful.
Bunsen (1842) and Grove (1839) created enhancements to batteries that used liquid electrodes to supply electricity.
In the year of 1859, Gaston Plante first developed the lead acid battery cell. This was the first form of rechargeable secondary battery. The lead acid battery is still in use for many industrial purposes. It is still most popularly used as car batteries.
In 1866 the battery was again developed by a French engineer, Georges Leclanche. It was a carbon-zinc wet cell battery known as the Leclanche cell. Crushed manganese dioxide mixed with a bit of carbon forms the positive electrode and a zinc rod is used as the negative electrode. Ammonium chloride solution is used as a liquid electrolyte. After some years Georges Leclanche himself improved his own design by replacing liquid ammonium chloride solution with ammonium chloride. This was the invention of the first dry cell.
In 1901 Thomas Alva Edison discovered the alkaline accumulator. Thomas Edison's basic cell had iron as the anode material (-) and nickel oxide as the cathode material(+). This is just one portion of an endless history of battery.
Step by Step Development in History of Batteries
|Luigi Galvani||Italy||1786||Animal Electricity|
|Alessandro Volta||Italy||1800||Voltaic Pile|
|John F. Daniell||Britain||1836||Daniell Cell|
|Sir William Robert Grove||Britain||1839||Fuel Cell|
|Robert Bunsen||German||1842||used liquid electrodes to supply electricity|
|Gaston Plante||France||1859||Lead Acid Battery|
|Georges Leclanche||France||1866||Leclanche Cell|
|Thomas Alva Edison||United States||1901||Alkaline Accumulator|
Working Principle of Battery
For understanding properly the basic principle of battery, we first should have some basic concept of electrolytes and electrons affinity. Actually when two dissimilar metals or metallic compounds are immersed in an electrolyte, there will be a potential difference produced between these metals or metallic compounds.
It is found that when some specific compounds are added to water, they are dissolved and produce negative and positive ions. This type of compound is called an electrolyte. The popular examples of electrolytes are almost all kinds of salts, acids, and bases, etc.
The energy released during accepting an electron by a neutral atom is known as electron affinity. As the atomic structure for different materials are different, the electron affinity of different materials will differ. If two different kinds of metals or metallic compounds are immersed in the same electrolyte solution, one of them will gain electrons and the other will release electrons. Which metal (or metallic compound) will gain electrons and which will lose them depends upon the electron affinities of these metals or metallic compounds. The metal with low electron affinity will gain electrons from the negative ions of the electrolyte solution. On the other hand, the metal with high electron affinity will release electrons and these electrons come out into the electrolyte solution and are added to the positive ions of the solution. In this way one of these metals or compounds gains electrons and another one loses electrons. As a result there will be a difference in electron concentration between these two metals. This difference of electron concentration causes a potential difference to develop between the metals. This potential difference or emf can be utilized as a source of voltage in any electronics or electrical circuits. This is a general and basic principle of battery.
All battery cells are based only on this basic principle. Let’s discuss one by one. As we said earlier Alessandro Volta developed the first battery cell, and this cell is popularly known as the simple voltaic cell. This type of simple cell can be created very easily. Take one container and fill it with diluted sulfuric acid as the electrolyte. Now immerse zinc and one copper rod in the solution and connect them externally by an electric load. Now your simple voltaic cell is completed. Current will start flowing through the external load.
Zinc in dilute sulfuric acid gives up electrons as below:
Zn → Zn + + + 2e -
These Zn + + ions pass into the electrolyte, and their concentration is very high near the zinc electrode. As a result of the above oxidation reaction, the zinc electrode is left negatively charged and hence acts as cathode. The dilute sulfuric acid and water disassociate into hydronium ions as given below:
H2SO4 + 2H2O → 2H3O+ + SO4 - -
Due to the high concentration of Zn + + ions near the cathode, the H3O+ ions are repelled towards the copper electrode and get discharged by removing electrons from the copper atoms. The following reaction takes place at the anode:
2H3O+ + 2e - → 2H2O + H2
As a result of the reduction reaction taking place at copper electrode, copper is left positively charged and hence it acts as the anode.
Daniell Battery Cell: The Daniell cell consists of a copper vessel containing copper sulfate solution. The copper vessel itself acts as the positive electrode. A porous pot containing dilute sulfuric acid is placed in the copper vessel. An amalgamated zinc rod dipping inside the sulfuric acid acts as the negative electrode.
When the circuit is completed, dilute sulfuric acid in the porous pot reacts with zinc so as to liberate hydrogen gas. The reaction takes place as below:
Zn + H2SO4 → ZnSO4 + H2
The formation of ZnSO4 in the porous pot does not affect the working of the cell, until crystals of ZnSO4 are deposited.
The hydrogen gas passes through the porous pot and reacts with the CuSO4 solution as below:
H2 + CuSO4 → H2SO4 + Cu
Copper so formed gets deposited on the copper vessel.