Energy storage involves converting energy from forms that are difficult to store to more conveniently or economically storable forms.

1. Energy Storage
Devices
• Introduction
• Solar Cell
• Fuel Cell
1. H2O2 Fuel Cell
2. Lithium Fuel Cell
• Ultra Capacitor

2. Introduction
O Energy storage is the capture of energy
produced at one time for use at a later
time.
O A device that stores energy is sometimes
called an accumulator.
O Energy storage involves converting
energy from forms that are difficult to store
to more conveniently or economically
storable forms.

3. Solar Cell
O A Solar Cell is basically
a p-n junction which
generates emf when
solar radiation falls on
the p-n junction.
O It works on the same
principle as the
photodiode, except that
no external bias is
applied and the junction
area is kept much larger
for solar radiation to be
incident because we are
interested in more
power.

4. Solar Cell
Construction :-
O A p-Si wafer is taken over
which a thin layer if n-Si is
grown on one-side by
diffusion process.
O The other side of p-Si is
coated with a metal (back
contact).
O On the top of n-Si layer,
metal finger electrode is
deposited which acts as
front contact.
O The metallic grid occupies
only a very small fraction of
the cell area so that light can
be incident on the cell from
the top.

5. Solar Cell
Working :-
O The generation of emf by a solar
cell, when light falls on, it is due to
the following three basic processes:
generation, separation and
collection.
1. Generation of e-h pairs due to
light close to the junction.
2. Separation of electrons and holes
due to electric field of the
depletion layer. Electrons are
swept to n-side and holes to p-
side.
3. The electrons reaching the n-side
are collected by the front contact
and holes reaching p-side are
collected by the back contact.
Thus p-side becomes positive and
n-side becomes negative giving
rise to photovoltage.

6. Solar Cell
Efficiency of a Solar Cell :-
O It is defined as the ratio of the total power
converted by the solar cell to the total solar
power available for energy conversion.

7. Solar Cell
Application of Solar Cells :-
O Industrial Applications
O Cathodic Protection
O Alarm Systems
O Defense Equipment
O Remote Aircraft beacons
O Automatic Meteorological Stations
O Social Applications
O Consumer Applications

8. Fuel Cell
H2O2 Fuel Cell :-
O The fuel cells convert
chemical energy to
electrical energy.
O In a combustion
process, oxygen
combines with the fuel to
produce heat and
combustion products
where as in fuel cell
oxygen combines with a
suitable element to
produce electricity and
oxidation products.

9. Fuel Cell
H2O2 Fuel Cell :-
O The fuel here is hydrogen.
O The anode has platinum powder
which act as a catalyst and splits
hydrogen into a positive ion and an
electron.
O The positive hydrogen moves
toward the cathode through the
electrolyte whereas electron moves
through the external circuit towards
the cathode.
O At the cathode the hydrogen
combines with the electron coming
through the external circuit and the
oxygen which is forced towards the
cathode to form water.
O The reaction at the cathode is
facilitated by nickel catalyst.

10. Fuel Cell
Lithium Cell :-
O Metallic lithium is used as the
anode, and an organic
electrolyte containing lithium
salt is used on the anode side.
O A lithium-ion solid electrolyte is
placed in between the two
electrolytic solutions as a
partition wall to separate the
cathode and anode sites.
O An alkaline water-soluble gel is
used as the aqueous electrolyte
for the cathode side and the
cathode consists of porous
carbon and an inexpensive
oxide catalyst.

11. Fuel Cell
Lithium Cell
Discharging reactions :-
O At anode: Li → Li+ + e-
O Lithium ions dissolve into
the organic electrolyte as
lithium ions and the
electrons are fed into the
conductor wire.
O The dissolved lithium ions
pass through the solid
electrolyte into the aqueous
electrolyte on the cathode
side.
O At cathode: O2 + 2H2O + 4e- →
4OH-
O Electrons are fed from the
conductor wire, and oxygen from
the air and the reduction reacts on
the surface of catalyst in the
porous carbon to produce hydroxyl
ions.
O They meet with lithium ions in the
aqueous electrolyte and produce
water-soluble lithium hydroxide.

12. Fuel Cell
Lithium Cell
Charging reactions :-
O At anode: Li+ + e- → Li
O Electrons are fed from the
conductor wire, and lithium
ions in the aqueous
electrolyte of the cathode
side pass through the solid
electrolyte and reach the
surface of the anode where
metallic lithium
precipitates.
O At cathode: 4OH- → O2
+ 2H2O + 4e-
O Oxygen gas is
generated.
O Generated electrons are
fed to the conductor
wire.

13. Ultra Capacitor
O Ultracapacitors are sometimes called supercapacitors or
electric double layer capacitor (EDLC) or
electrochemical supercapacitors.
O Ultracapacitors are a type of electrical components that
are capable of holding electrical charge nearly 10,000
times more than a standard electrolytic capacitor. They
have the highest available capacitance values per unit
area and the greatest energy density of all capacitors.
O They bridge the gap between conventional capacitors
and rechargeable batteries.

14. Ultra Capacitor
O During charging, the electrically
charged ions in the electrolyte
migrate towards the electrodes
of opposite polarity due to the
electric field between the
charged electrodes created by
the applied voltage.
O Thus two separate charged
layers are produced.
O Although similar to battery, the
double layer capacitor depends
on electrostatic action.
O Since no chemical action is
involved the effect is easily
reversible and the typical cycle
life is hundreds of thousands of
cycles.

15. Ultra Capacitor
O Advantages :-
1. Cell voltage determined by the circuit application, not
limited by the cell chemistry.
2. Very high cell voltages possible.
3. High power available.
4. High power density.
5. Simple charging methods. No special charging or voltage
detection circuits required.
6. Very fast charge and discharge. Can be charged and
discharged in seconds. Much faster than batteries.
7. No chemical actions.
8. Can not be overcharged.
9. Long cycle life of more than 500,000 cycles at 100%
DOD.
10. Long calendar life 10 to 20 years.
11. Low impedance

16. Presented by :-
O Name – Priyansh J. Thakar
O Id. No. – 16BECEG082
O Batch – CE 2 : A