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BATTERIES m.pptx
1. BATTERIES
P. A. COLLEGE OF ENGINEERING AND TECHNOLOGY
(An Autonomous Institution)
POLLACHI-642 002
Accredited by NAAC with ‘A’ Grade
DEPARTMENT OF COMPUTER SCIENCE AND ENGINEERING
Accredited by NBA
Presented by,
Manosakthi T
2. INTRODUCTION
• Definition: devices that transform chemical energy into electricity
• Every battery has two terminals: the positive cathode (+) and the
negative anode (‐)
• Functioning
• Device switched on ‐> chemical reaction started ‐ electrons produced
electrons
travel from (‐) to (+) electrical work is produced
3. PRIMARY AND SECONDARY BATTERIES
• Primary batteries are disposable because their electrochemical
reaction cannot be reversed.
• Secondary batteries are rechargeable, because their electrochemical
reaction can be reversed by applying a certain voltage to the battery in
the opposite direction of the discharge.
5. Leclanche cell
zinc-carbon battery, also called the Leclanche cell, is a traditional
general-purpose dry cell. The Leclanche cell is a battery invented and
patented by the French scientist Georges Leclanche in 1866.
Electrolyte -> Ammounium chloride
Cathode -> Carbon
Anode -> Zinc
Deplorizer -> Manganese dioxide
Applications:
the most common type of battery, is used in flashlights, electronic
devices such as the Walkman and Game Boy, and many other devices.
7. Advantages:
The cost of this battery cell is quite low. Various shapes, sizes and
capacities of these cells are easily available. Long traditional reliability.
Disadvantages:
Its energy density is quite low.
It gives poor service in low temperature.
It has poor leakage resistance.
Cannot perform efficiently at high current drain application.
8. Lead-acid Battery
The lead–acid battery is a type of rechargeable
battery first invented in 1859 by French physicist Gaston Planté.
It is the first type of rechargeable battery ever created. Compared
to modern rechargeable batteries, lead–acid batteries have
relatively low energy density.
9. Working:
In the fully charged state, the negative plate consists of lead,
and the positive plate is lead dioxide. The electrolyte solution has
a higher concentration of aqueous sulfuric acid, which stores
most of the chemical energy.
Negative plate reaction
Pb(s) + HSO−
4(aq) → PbSO4(s) + H+(aq) + 2e−
The release of two conduction electrons gives the lead
electrode a negative charge.
Positive plate reaction
PbO2(s) + HSO−
4(aq) + 3H+(aq) + 2e− → PbSO4(s) + 2H2O(l)
taking advantage of the metallic conductivity of PbO
2.
10. • The total reaction can be written as
Pb(s) + PbO2(s) + 2H2SO4(aq) → 2PbSO4(s) + 2H2O(l)
Discharge
In the discharged state both the positive and negative plates
become lead(II) sulfate (PbSO4), and the electrolyte loses much of its
dissolved sulfuric acid and becomes primarily water.
Applications:
Lead-acid batteries are the most widely
and commonly used rechargeable batteries in
the automotive and industrial sector.
11. Advantages:
Cheap, powerful, easily rechargeable, high power output
capability.
Disadvantages:
Very heavy, batteries tend to be very large bricks because
energy density is very low.
12. Nickel-Metal Battery
A nickel metal hydride battery (NiMH or Ni–MH) is a type of rechargeable battery.
The chemical reaction at the positive electrode is similar to that of the nickel–cadmium
cell (NiCd), with both using nickel oxide hydroxide (NiOOH). However, the negative electrodes
use a hydrogen-absorbing alloy instead of cadmium. NiMH batteries can have two to three
times the capacity of NiCd batteries of the same size, with significantly higher energy density,
although much less than lithium-ion batteries
Charging: When the battery is put on charging, the hydroxyl (OH–)
ions move towards the anode, whereas the potassium (K+) ions
move towards the cathode. The following chemical reaction takes
place during charging:
At anode: Ni(OH)2 + 2OH —> Ni(OH)4
At cathode: Fe(OH)2 + 2K —> Fe + 2 KOH
13. Discharging: When the battery discharges, the potassium hydroxide (KOH)
is dissociated into potassium (K+) and hydroxyl (OH–) ions. The hydroxyl ions
go to cathode and potassium ion go to the anode. The following chemical
reaction takes place during discharging:
At cathode: Fe + 2OH –> Fe(OH)2
At anode: Ni(OH)4 + 2K —-> 2KOH + Ni(OH)4
Total reaction:
2NiOOH.H2O+Fe → 2Ni(OH)2+Fe(OH)2
14. Advantages:
higher specific energy with fewer toxic metals, less effect
on memory and generates high peak power. It also has good
deep discharge and is environmentally friendly.
Disadvantages:
high cost, strong self-rate, and the fact that they produce
a large amount of heat at extreme temperature
