Improving
Energy
Storage using
Various
Materials
By: Jamison Chang, Carlos Hernandez,
Lianne Monterroso, Jeanene Tomecek
Overview
 Attaining and storing energy can be done in various ways. Each method has its
pros and cons, but engineers are constantly finding ways to make those methods
more efficient and inexpensive.
 Effect of technologies future based on lowered cost, efficiency, and the transfer
from nonrenewable processes to greener processes that are better for the
environment.

-Solar Cells
 -Biosolar Cell
-Dye-Sensitized Solar Cells
-Thermal Batteries
What is a Solar Cell?

Use semiconductors like silicon to
absorb light

Impurities are added to allow the
charged particles to move around –
Hence, electrical conduction

N-type impurities: extra electrons
in the material

P-type impurities: extra protons
in the material
How does a solar cell work?
http://science.howstuffworks.com/environmental/energy/solar-cell.htm

When the p-type and n-type are
put together the electrons move
toward the p-n boundary and
form an electrical field

When light hits the cell, electrons
begin to move from the p to the n
side and create an electrical
current
Efficiency of
Solar Cell
-Can only absorb 15 to 25% of
solar energy
-Why?
-Not all light rays are strong
enough to bump an electron
-Silicon is a semiconductor so it
is not very efficient at
conducting electrons compared
to a conductor
Dye-sensitized solar cell
One design type

Made from inorganic material
called titania with organic dye on
the surface

Dye absorbs light and generates
electrons

The titania then moves the
electrons to the electrode

Another Design Type

Inorganic material made from
alumina nanoparticles with
perovskite(organic/inorganic)
instead of organic dye

Perovskite does same job as dye

BUT it also does what the titania
does in the other type of cell
DyeSensitized
Solar Cell
-The efficiency of the first
design is about 12.3%
-The efficiency of the
perovskite: about 10.9%
-Both efficiences small
compared to photovoltaic solar
cell
-Efficiency is offset by cost.
Relatively inexpensive dye solar
cells.
Biosolar
Energy from
Plants
• A new breakthrough in
“green” energy from Dr.
Barry Bruce and researchers
from MIT:
• Photosystem – I ( or PS-I: a key
component of photosythesis) is
extracted from blue-green algae
• The complex is engineered to react
with a semi-conductor, creating a
“green” solar cell.
• Energy is produced with sunlight
exposure
What does this
solar cell consist
of ?
• Non-biological materials
• Small tubes of zinc oxide
• Tubes attract PS-I
• Biological components
• PS-I
• When both materials are
combined and illuminated,
electrons are transferred to
the ZnO to produce an
electrical current.
Illustration of the Biosolar cell
Source: http://www.nature.com/srep/2012/120202/srep00234/full/srep00234.html
Benefits of
Biosolar Energy
•
•
•
•
Potential to make “green”
energy significantly cheaper
Requires significantly less natural
resources than most biofuels
Does not release toxic chemicals
during production as opposed to
photovoltaic solar power systems
Uses completely renewable
resources (algae)
Future
Improvements
• Possible optimizations for the
current technology:
• Can better orient PS-I to semi-
conductor
• More biofriendly electrolytes can be
matched with photoanode
substances
• The long-term performance
of the biophotovoltaic system
can be measured.
•
Why?
• 90% of energy generation
is consumed or wasted
thermally
• Significant role in heating
and cooling, solar energy
harvesting, etc.
•
Problem: Finding efficient
and cost-effective ways to
store thermal energy
•
Two groups of materials for
thermal batteries:
thermophysical and
thermochemical
Thermal
Batteries
http://micro.magnet.fsu.edu/electromag/electricity/batteries/thermal.html
Potential Impacts
•
Solar power plants can generate
electricity 24 hours a day
•
Increase energy output of nuclear
plants
•
Improve performance of electric
vehicles
•
Decrease fossil-fuel based
electricity use
https://en.wikipedia.org/wiki/Sustainable_development
 Energy storage relies on
Thermophysical
Materials
http://community.controlglobal.com/content/power-scavenging-strikes-again
changes in physical state
of material
 Achieved through
sensible heat and/or
latent heat
 Stores heat in an object to
use later
 Need to insulate system
to minimize heat losses
 Ex: Solar thermal power
plants store solar energy
by heating molten salts
Thermochemical
Methods
•
Chemical reactions reversibly
store energy
• Do not require insulation
• Low energy density: requires large
volume
• Ex: ZnO + heat -> Zn + ½ O2; Zn + H2O
-> ZnO + H2
http://www.pre.ethz.ch/research/projects/?id=solarhydroviaredox
Limitations

Thermophysical: materials have high
volumetric energy density but low
gravimetric energy density

Thermochemical: materials have high
gravimetric density but low volumetric
energy density

Mechanical compression…

Current thermal energy storage materials
performance

Lithium-ion battery: energy density ~ 5000
MJ/m3 and specific energy ~ 1.3 MJ/kg

Performance needs to improve to become
competitive with current technology
Searching for a Better Thermal Battery. Ilan Gur et
al. Science 335, 1454 (2012).
Recent Developments

ARPA-E High Energy Advanced Thermal
Storage program
 Goal: “develop revolutionary, cost
effective ways to store thermal energy”
 High-temperature solar thermal
energy storage
 Create synthetic fuel from
sunlight by converting sunlight to
heat
 Improve the driving range of
electric vehicles and enable
thermal management of thermal
combustion engine vehicles

MIT: Efficient Heat Storage Materials

University of Florida: Solar
Thermochemical Fuel Production

UT-Thermal Batteries for Electric Vehicles
MIT: Efficient Heat Storage
Materials
Traditional salt encapsulated for
thermal storage
Source:
http://www1.eere.energy.gov/solar/sunshot/csp_newsletter.
html

Need efficient thermal storage to
maximize capacity of solar and nuclear
plants. Current solar power plants only
run at 25% capacity because there is no
generation at night

Goal is to find materials with a large
latent heat, able to store >1 MJ/kg.
Hope to reduce cost of thermal energy
storage by 75%

Considering metallic alloys instead of
traditional salts
University of
Florida: Solar
Thermochemical
Fuel Production
•
•
Klausner et al. University of Florida. Solar Fuel: Pathway
to a Sustainable Energy Future.
http://www.floridaenergysummit.com/pdfs/presentations
2012/klausner.pdf
•
Store solar energy through a
thermochemical conversion
of carbon dioxide and water
to fuel
Reactor converts solar
energy to syngas, which can
be used to produce gasoline
Goal: lower cost of
production of syngas
UT-Thermal
Batteries for
Electric Vehicles
•
•
http://www.tmi.utexas.edu/facultyresearch-spotlight/dr-li-shi/
•
Batteries based on silicide
materials for waste heat
recovery
Currently, inefficient heating
and cooling of EVs increase
load on the battery
Thermal storage system can
take the waste heat and
convert it to electrical power
and can increase driving
range
Renewable Cathode Materials from
Biopolymer/Conjugated Polymer
Interpenetrating Networks
 What are they?
 Renewable and cheap materials in
electrodes that can store charge and
create a renewable energy system
when enough charge density is
acquired.
http://www.intechopen.com/books/composites-and-theirproperties/c-li2mnsio4-nanocomposite-cathode-material-for-li-ionbatteries
Advantages
Electroactive materialChanges shape as charge is passed
through it
http://www.electricfoxy.com/2010/03/exploring-the-potential-of-electro-active-polymers/

Conjugated polymers with added
quinone groups give improved
charge storage

The combined redox processes of
polymer and redox anion
contribute to charge capacity in
materials.

It is desirable to use the quinone
redox function in electroactive
materials to enhance chargestorage capacity.
Limitations

Does it work with all types of
polymers?
 No, renewable energy systems
based on intermittent sources
require methods for power
balancing over time, and thus
some means of storage.
 Organic polymers do not
provide enough charge density
to work in secondary batteries
and super.
 Inorganic insertion electrodes
are much better at charge
storage.
Inorganic Electrodes
http://www.gizmag.com/ibm-lithium-air-battery/22310/
Methods

Redox Functions (Redox processes of polymer &
Redox anion)

Conjugated polymers with added quinone groups

Electrochemical polymerization (to generate solids
with extremely high conductance)
Andreas Mershin, Kazuya Matsumoto, Liselotte Kaiser, Daoyong Yu, Michael Vaughn,
Md. K. Nazeeruddin, Barry D. Bruce, Michael Graetzel, Shuguang Zhang. Self-assembled
photosystem-I biophotovoltaics on nanostructured TiO2 and ZnO. Scientific Reports, 2012
Cyclic Voltammetry
•
Cyclic voltammetry, a type of potentiodynamic electrochemical
measurement, of polypyrrole shows the two redox waves that
correspond to the reaction involved.
Fig. 1CV of the Ppy(Lig) composite electrode. (A) Voltammograms recorded between 0.1 and 0.4 V.
(B) Voltammograms recorded between 0.1 and 0.75 V versus Ag/AgCl, scan rates 5 to 25 mV s−1 (inner
to outer). (C) Dependence of the redox peak currents on scan rate. Film thickness, 0.5
Andreas Mershin, Kazuya Matsumoto, Liselotte Kaiser, Daoyong Yu, Michael Vaughn, Md. K. Nazeeruddin, Barry D. Bruce, Michael Graetzel, Shuguang
Zhang. Self-assembled photosystem-I biophotovoltaics on nanostructured TiO2 and ZnO. Scientific Reports, 2012
Galvanostatic discharge curves for (A)
thinner (0.5 μm) and (B) thicker (1.9 μm)
Ppy(Lig) composite film. Two regions are
visible, assigned to electrochemical activity
of Ppy and lignin-derived quinones, along
with linear regression lines used for
capacitance analysis. For clarity, in (A) the
regression lines are shown for the highest
discharge current only; the other ones nearly
overlap with each other. rent redox
potentials
Andreas Mershin, Kazuya Matsumoto, Liselotte Kaiser, Daoyong Yu, Michael Vaughn,
Md. K. Nazeeruddin, Barry D. Bruce, Michael Graetzel, Shuguang Zhang. Self-assembled
photosystem-I biophotovoltaics on nanostructured TiO2 and ZnO. Scientific Reports, 2012
Discharge under
galvanostatic
conditions
•
The galvanostic discharge
curves for polypyrrole and
quinone show that the
charge capacity for
polypyrrole is about 30-35
mAh(milliamp-hour) /g and
about 40 mAh/g for
quinone.
The Implications of
Using Inorganic
Biopolymers for charge
storage
•
•
•
Low-cost
Safer and non-toxic operation
in water
Can be further improved
through research to get
greater charge and energy
storage.
References

Getting Moore from Solar Cells. David J. Norris and Eray S.
Aydil. Science 2 November 2012: 338 (6107), 625-626.

Renewable Cathode Materials from Biopolymer/Conjugated
Polymer Interpenetrating Networks. Grzegorz Milczarek and
Olle Inganäs. Science 23 March 2012: 335 (6075), 1468-1471.

Searching for a Better Thermal Battery. Ilan Gur, Karma Sawyer,
and Ravi Prasher. Science 23 March 2012: 335 (6075), 1454-1455

Andreas Mershin, Kazuya Matsumoto, Liselotte Kaiser,
Daoyong Yu, Michael Vaughn, Md. K. Nazeeruddin, Barry D.
Bruce, Michael Graetzel, Shuguang Zhang. Self-assembled
photosystem-I biophotovoltaics on nanostructured TiO2 and ZnO.
Scientific Reports, 2012