Batteries convert chemical energy into electrical energy through redox reactions. They consist of an anode, cathode, and electrolyte. Primary batteries are non-rechargeable while secondary batteries are rechargeable. During discharge, oxidation occurs at the anode and releases electrons while reduction occurs at the cathode and consumes electrons. Common battery types include lead-acid, nickel-cadmium, nickel-metal hydride, and lithium-ion. Metal-air batteries have high energy density and use oxygen from the air as the cathode reactant, providing advantages over traditional batteries.

1. Batteries
Battery is a power source that acts like a transducer that converts chemical energy to electrical
energy
It consists of
1. Anode – Source
2. Cathode – Sink
3. Electrolyte – Electronic/ionic transport medium

2. Types of batteries
Primary – Non rechargeable
Ex. Alkaline batteries
Secondary – Rechargeable Batteries
Ex. Lead Acid, Ni-cd, Li-ion

3. Basic Structure

4. Reactions in a battery
Anode Reaction :
It is Oxidation reaction
It Releases Electrons e-
Hence it is a negative Electrode
Cathode Reaction :
It is Reduction reaction
It consumes Electrons
Hence it is a positive electrode
Electrolyte :
Ion Conduction medium
Conducts the passage of electrons between the electrodes

5. Battery Specifications
Types of Battery Anode Cathode Electrolyte Applications
Lead Acid Pb PbO2 H2SO4 Emergency Power Utilities, Portable tools,
Automotive Starting Lighting and Ignition
(SLI), Industrial Trucks
Nickel Cadmium Cd NiOOH KOH Aircraft Batteries, Communication
Equipment, memory backup, Photography
equipment
Nickel-Metal
Hydride
MH NIOOH KOH Portable Electronic Devices
Nickel-Iron Fe NIOOH KOH Railway Signaling, Stationary Power supply
Lithium-Ion Carbon LiCoO2 LiPF6 in EC:PC Electric Vehicles, Cell phones, Laptops,
Portable Devices
Lithium polymer Li LiCoO2 Solid Polymer
films
Electric Vehicles, Credit cards, Slim
Electronic Devices

6. Metal-Air Battery
Advantage
1. Durable
2. Efficient
3. Long run
4. Cheap rate
5. High Energy density

7. Principle
It's a cell metal-air electrochemistry, which
uses an anode made of pure metal and an
external cathode of ambient air
The Fundamental working principle of MAB is
to electrochemically reduce O2 from the air
and oxidize the metal electrode, resulting in
the formation of solid metal oxides that may
be recycled
The atmospheric oxygen dissociates while the
metal of the anode is oxidized, this generates a
flow of electrons Basic Structure

8. Construction
This system comprises three basic parts:
a metal anode,
a porous air cathode,
an electrolyte that separates the two
electrodes from one another

9. Composition
Battery Anode Cathode Electrolyte
Metal Air battery lithium Li, sodium Na,
iron Fe, zinc Zn, and
other elements
Air Non aqueous
electrolytes (lithium-air,
potassium-air, and
sodium-air)
Aqueous electrolytes
(magnesium, aluminium,
iron, or zinc)

10. Electro-chemical Reaction
Metal changes into ions on the anodic electrode, while the oxygen transforms into hydroxide
ions at the cathodic electrode
 The metallic ions transition takes place from the anode to cathode.
The diffusion of oxygen into the MAB occurs via a layer known as the gas diffusion layer.
 The behavior of oxygen in an aqueous electrolyte medium differs from that of oxygen in a non
aqueous electrolyte.
During the transition of the metal into metallic ions, electrons are produced, and the metallic
ions subsequently dissolve into the electrolyte.
 During a charging operation, all of these steps are reversed.

11. Electro-chemical Reaction Cont.
In general, the air cathode should own three
features:
1) Massive and connected channels for the
diffusion of gas and deposition of discharge
product.
2) Good electrical conductivity to facilitate the
electron transportation.
3) Highly catalytic activity for oxygen reduction
reaction and oxygen evolution reaction.
Carbon based materials are commonly used in
metal–air batteries due to their excellent
electrical conductivity and high porosity

12. Electro-chemical Reaction Cont.

13. Aluminium-air batteries
Aluminium–air batteries produce current from
the reaction of oxygen in the air with aluminium.
Advantages: - This batteries have one of the
highest volumetric energy densities of all metal-
air batteries.
Disadvantages:
Expensive anode preparation. - Problems with
the product removal when using traditional
electrolytes.
Aluminium–air batteries are non-rechargeable
but it is possible to recharge the battery with
new aluminium anodes by recycling the hydrated
aluminium oxide.

14. Lithium-air batteries
A Li-air battery creates voltage when O2 reacts
with the positively charged lithium ions to
form lithium peroxide (Li2O2).
The main problem of the Li-air batteries is the
electrolyte. Lithium reacts violently with water
so there is the necessity to find new
electrolytes.
The other problem of lithium-air batteries is
that Li2O2 is a very bad electron conductor. If
deposits of Li2O2 grow on the electrode
surface that supplies the electrons for the
reaction, it eventually kills off the reaction

15. Iron-Air Batteries
Iron–air rechargeable batteries promise a higher
energy density than present-day lithium-ion
batteries.
The main raw-material of this technology is iron
oxide (rust) which is an abundant and cheap
material, non-toxic, inexpensive and
environmentally friendly.
In conjunction with a fuel cell this enables the
system to behave as a rechargeable battery
creating H2O/H2 via production/consumption of
electricity.
Furthermore, this technology has minimal
environmental impact as it could be used to store
energy from intermittent solar and wind power
sources, developing an energy system with low
carbon dioxide emissions.

16. Magnesium–air batteries
A Mg-air battery is composed of an Mg (or Mg
alloy) anode, an air cathode and a saline
electrolyte.
The Mg–air battery is a promising
electrochemical energy storage and
conversion device since Mg is abundant on the
earth, has a high reaction activity, is light
weight, has low toxicity and has relatively high
safety.
The Mg–air battery can be re-used
mechanically by replacing the spent Mg anode
and electrolyte with a fresh Mg anode and
electrolyte.

17. Zinc-air batteries
Zinc–air batteries are metal-air batteries
powered by oxidizing zinc with oxygen from the
air.
They are considered non-rechargeable but can
be mechanically recharged by changing the zinc
anode and the electrolyte.
These batteries have high energy densities and
are relatively cheap to produce. Sizes range from
very small button cells to very large batteries
used for electric vehicle propulsion.
The operating life of a zinc–air cell depends on its
interaction with its environment. The electrolyte
loses water more rapidly in conditions of high
temperature and low humidity.

18. Comparison-General