Define battery in physics
Combination of number of cells form a battery.
What are the two main types of cells
Cell are divided into two classes as under:
1- Primary cell
2- Secondary Cell
Primary cell
A cell which cannot be recharged again is called primary cell. Primary cells are uses in Watches, TV Reboot Control, Radio Torch Light etc. It has smaller in size. It has lighter in weight. It has short life time. Its initial cost is low. It has a irreversible chemical reaction. It has high value of energy density. It has high internal resistance. It has low discharging rate. It has dry electrolyte in the form of powder or highly viscous paste so it also called dry cell.
Secondary Cell
A cell which can be recharged again and again is called secondary cell. They are used as mobile battery, laptop battery and UPS battery. It has larger size. It is heavier in weight. It has long life time. It is expensive. It has reversible chemical reaction. It has low value of energy density. It has low internal resistanc. It has fast discharge rate. They are made up of wet cell and molten salt.
Dry Cell
It is basically a Galvanic cell. It is type of electric battery. French engineer George leclanche.
Parts of dry cell dry cell
Dry cell consists of following parts:
Anode
The electrode at which oxidation reaction take place is called anode. In Oxidation reaction electrons are release. In dry cell a carbon (graphite) Rod is act as anode. Anode may be positive or negative.
Cathode
Cathode the the electrode at which reduction reaction take place is called cathode. In reduction reaction electrons are obsorbed. Cathode may be positive or negative. In dry cell Cathode is the zinc Container.
Electrolyte :
A) A paste of amino acids include ride in place around the graphic rod. This paste act as electrolyte.
B) Around the paste of a porous membrane is placed which act as separater. This separator keep the cathode and anode away from each other.
C) Around the separator past of ( NH4Cl + ZnCl2 ) is field this paste at an electrolyte also.
D) Around the paste of nh4cl 4 a metal container sheet of zinc is fixed in the form of cylinder.
Redox Reactions :
The sum of oxidation and reduction reaction is called Redox reaction.
It should be noted that while constructing a cell two metals having different value of reduction potential must be used as anode and cathode.
The metal having greater reduction potential has greater ability to again electrons and will act as cathode.
Voltage Dry Cell :
It is the voltage of cell before using it in any circuit it is called EMF of cell. It depend upon the nature of material of electrolyte used in the cell.
Current Rating of the Dry Cell
Current rating of dry cell is the amount of current which the cell can supply to the external circuit and it depend upon the size of cell.
Zinc Carbon Cell
Zinc carbon is dry cell and is primary cell. it is used only once and cannot be charged again.
Construction of zinc Carbon cell
it consists of following
Anode
It is a metal container made of zinc. It acts as negative electrode. Oxidation reaction take the anode and it and donates electrons.
Cathode
Cathode is a carbon graphite rod. It acts as positive electrode. Reduction reaction take place the cathode and it accept electron donate by the anode.
Electrolyte :
Around the carbon rod, there is a paste of mno2 and carbon powder.
Separator
A separator is placed around the paste of mno2 and carbon. It acts as porous membrane or separator
Second electrolyte
Around the separator a think paste of nh4cl zncl2 is field which act as second electrolyte. Zinc carbon cell can provide maximum voltage upto 1.5 voltage. The chemical reaction takes place in this cell are Irreversible. These cells have different sizes and their current raiting is up to 0.25 A.
Alkaline Battery
It is a dry primary battery. It takes its energy from the reaction between zinc and mno2. It has higher energy density and life time as compared to zinc carbon cell.
They are used in MP3 player, CD players, digital cameras, toys and flashlights.
The current rating of Alkaline battery is greater than zinc carbon cell because mno2 used in this battery has greater density.
Its current rating is 3 to 5 times larger than any other battery. Its emf is 1.5 volt.
Construction of Alkaline Battery
Alkaline battery consists of the following part
Anode
Its anode made of zinc
Cathode
Its Cathode is mno2.
Electrolyte
The electrolyte used in this cell is KOH.
Maganese Alkaline Cell
It is primary cell whose anode is made up of zinc and Cathode is mno2. It anode and cathode are placed inside the leake proof Steel can. It electrolyte has greater conductivity and its EMF also 1.5 V.
Mercury cell
Mercury cell is a primary cell and its anode is made of zinc and cathode consists of mercuric oxide. It electrolyte is KOH. It's EMF or open circuit voltage is 1.35 V. The oxidation reaction takes place at anode and reduction reaction take place at cathode. Mercury cells are available in different shapes and sizes. Its smallest size is 3 mm thick and 12.5 mm in diameter.
Lead Acid Battery
Lead acid battery is the secondary battery. The chemical reaction taking place in this battery is reversible. This battery can be recharged after this charging by passing electric current through it. In discharging chemical energy in converted into electrical energy while in charging electrical energy is converted into chemical energy.
Construction
Lead Acid Battery consists of single box in which 6 cells are placed side by side each having a voltage of two voltage, so the total voltage of battery is 12 voltage. This battery has larger weight.
Why is preferred over light weight batteries? Because it can provide large surges of electricity to start cooled engine of automobile. It electrolyte are made of Led oxide which are isolated from each other by separator. These electrodes are deep in concentrated solution of H2So4. It has 6 cells are connected in series combination with each other. In this combination positive end of cell is connected to negative end of another cell with the help of connector.
