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ABSTRACT
The Batteries form a significant
part of many electronic devices. Typical
electrochemical batteries or cells convert
chemical energy into electrical energy.
Batteries based on the charging ability
are classified into primary and secondary
cells. Secondary cells are widely used
because of their rechargeable nature.
Presently, battery takes up a huge
amount of space and contributes to a
large part of the device's weight. There is
strong recent interest in ultrathin,
flexible, safe energy storage devices to
meet the various design and power needs
of modern gadgets. New research
suggests that carbon nanotubes may
eventually provide the best hope of
implementing the flexible batteries
which can shrink our gadgets even more.
The paper batteries could meet the
energy demands of the next generation
gadgets. A paper battery is a flexible,
ultra-thin energy storage and production
device formed by combining carbon
nanotubes with a conventional sheet of
cellulose-based paper. A paper battery
acts as both a high-energy battery and
super capacitor, combining two
components that are separate in
traditional electronics. This combination
allows the battery to provide both long-
term, steady power production and bursts
of energy. Non-toxic, flexible paper
batteries have the potential to power the
next generation of electronics, medical
devices and hybrid vehicles, allowing for
radical new designs and medical
technologies.
The various types of batteries followed
by the operation principle,
manufacturing and working of paper
batteries are discussed in detail.
Keywords: paper batteries, flexible,
carbon nanotubes
INTRODUCTION TO
BATTERIES
An electrical battery is one or more
electrochemical cells that convert stored
chemical energy into electrical energy.
Since the invention of the first battery in
1800 by Alessandro Volta, batteries have
become a common power source for
many household and industrial
applications.
Batteries are represented symbolically as
1
Fig. 1a Symbolic view
Fig. 1b conventional battery
Electrons flow from the negative
terminal towards the positive terminal.
Based on the rechargeable nature
batteries are classified as
a. Non rechargeable or
primary cells
b. Rechargeable or
secondary cells
Based on the size they are classified as
a. Miniature batteries
b. Industrial batteries
Based on nature of electrolyte
a. Dry cell
b. Wet cell
Terminologies
1. Accumulator - A rechargeable
battery or cell
2. Ampere-Hour Capacity - The
number of ampere-hours which
can be delivered by a battery on a
single discharge.
3. Anode - During discharge, the
negative electrode of the cell is
the anode. During charge, that
reverses and the positive
electrode of the cell is the anode.
The anode gives up electrons to
the load circuit and dissolves into
the electrolyte.
4. Battery Capacity - The electric
output of a cell or battery on a
service test delivered before the
cell reaches a specified final
electrical condition and may be
expressed in ampere-hours, watt-
hours, or similar units. The
capacity in watt-hours is equal to
the capacity in ampere-hours
multiplied by the battery voltage.
5. Cutoff Voltage final - The
prescribed lower-limit voltage at
which battery discharge is
considered complete. The cutoff
or final voltage is usually chosen
so that the maximum useful
capacity of the battery is realized.
6. C - Used to signify a charge or
discharge rate equal to the
capacity of a battery divided by 1
hour. Thus C for a 1600 mAh
battery would be 1.6 A, C/5 for
2
the same battery would be 320
mA and C/10 would be 160 mA.
7. Capacity - The capacity of a
battery is a measure of the
amount of energy that it can
deliver in a single discharge.
Battery capacity is normally
listed as amp-hours (or milli
amp-hours) or as watt-hours.
8. Cathode - Is an electrode that,
in effect, oxidizes the anode or
absorbs the electrons. During
discharge, the positive electrode
of a voltaic cell is the cathode.
When charging, that reverses and
the negative electrode of the cell
is the cathode.
9. Cycle - One sequence of
charge and discharge.
10. Cycle Life - For
rechargeable batteries, the total
number of charge/discharge
cycles the cell can sustain before
its capacity is significantly
reduced. End of life is usually
considered to be reached when
the cell or battery delivers only
80% of rated ampere- hour
capacity.
11. Electrochemical
Couple - The system of active
materials within a cell that
provides electrical energy storage
through an electrochemical
reaction.
12. Electrode - An
electrical conductor through
which an electric current enters
or leaves a conducting medium
13. Electrolyte - A
chemical compound which, when
fused or dissolved in certain
solvents, usually water, will
conduct an electric current.
14. Internal Resistance -
The resistance to the flow of an
electric current within the cell or
battery.
15. Open-Circuit Voltage
- The difference in potential
between the terminals of a cell
when the circuit is open (i.e., a
no-load condition).
16. Voltage, cutoff -
Voltage at the end of useful
discharge. (See Voltage, end-
point.)
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17. Voltage, end-point -
Cell voltage below which the
connected equipment will not
operate or below which operation
is not recommended.
Principal of Operation of
cell
A battery is a device that converts
chemical energy directly to electrical
energy. It consists of a number of voltaic
cells. Each voltaic cell consists of two
half cells connected in series by a
conductive electrolyte containing anions
and cations. One half-cell includes
electrolyte and the electrode to which
anions (negatively charged ions)
migrate, i.e., the anode or negative
electrode. The other half-cell includes
electrolyte and the electrode to which
cations (positively charged ions)
migrate, i.e., the cathode or positive
electrode. In the redox reaction that
powers the battery, cations are reduced
(electrons are added) at the cathode,
while anions are oxidized (electrons are
removed) at the anode. The electrodes do
not touch each other but are electrically
connected by the electrolyte. Some cells
use two half-cells with different
electrolytes. A separator between half
cells allows ions to flow, but prevents
mixing of the electrolytes.
Fig.
1.2 principle operation
Each half cell has an electromotive force
(or emf), determined by its ability to
drive electric current from the interior to
the exterior of the cell. The voltage
developed across a cell's terminals
depends on the energy release of the
chemical reactions of its electrodes and
electrolyte. Alkaline and carbon-zinc
cells have different chemistries but
approximately the same emf of 1.5 volts.
Likewise NiCd and NiMH cells have
different chemistries, but approximately
the same emf of 1.2 volts. On the other
hand the high electrochemical potential
changes in the reactions of lithium
compounds give lithium cells emf of 3
volts or more.
Types of batteries
Batteries are classified into two broad
categories. Primary batteries irreversibly
(within limits of practicality) transform
chemical energy to electrical energy.
When the initial supply of reactants is
exhausted, energy cannot be readily
restored to the battery by electrical
means. Secondary batteries can be
recharged. That is, they can have their
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chemical reactions reversed by supplying
electrical energy to the cell, restoring
their original composition.
Primary batteries: This can produce
current immediately on assembly.
Disposable batteries are intended to be
used once and discarded. These are most
commonly used in portable devices that
have low current drain, are only used
intermittently, or are used well away
from an alternative power source, such
as in alarm and communication circuits
where other electric power is only
intermittently available. Disposable
primary cells cannot be reliably
recharged, since the chemical reactions
are not easily reversible and active
materials may not return to their original
forms. Battery manufacturers
recommend against attempting
recharging primary cells. Common
types of disposable batteries include
zinc-carbon batteries and alkaline
batteries.
Secondary batteries: These batteries
must be charged before use. They are
usually assembled with active materials
in the discharged state. Rechargeable
batteries or secondary cells can be
recharged by applying electric current,
which reverses the chemical reactions
that occur during its use. Devices to
supply the appropriate current are called
chargers or rechargers.
Fig. 1.3a Primary cell
Fig. 1.3b Secondary cell
Recent developments
Recent developments include
batteries with embedded functionality
such as USBCELL, with a built-in
charger and USB connector within the
AA format, enabling the battery to be
charged by plugging into a USB port
without a charger USB Cell is the brand
of NiMH rechargeable battery produced
by a company called Moixa Energy. The
batteries include a USB connector to
allow recharging using a powered USB
port. The product range currently
available is limited to a 1300 mAh.
5
Fig. 1.4 USB cell
Life of battery
Even if never taken out of the original
package, disposable (or "primary")
batteries can lose 8 to 20 percent of their
original charge every year at a
temperature of about 20°–30°C. [54]
This is known as the "self-discharge"
rate and is due to non-current-
producing "side" chemical reactions, which occur within the cell even if no
load is applied to it. The rate of the side
reactions is reduced if the batteries are
stored at low temperature, although
some batteries can be damaged by
freezing. High or low temperatures may
reduce battery performance. This will
affect the initial voltage of the battery.
For an AA alkaline battery this initial
voltage is approximately normally
distributed around 1.6 volts.
Rechargeable batteries self-discharge
more rapidly than disposable alkaline
batteries, especially nickel-based
batteries a freshly charged NiCd loses
10% of its charge in the first 24 hours,
and thereafter discharges at a rate of
about 10% a month. Most nickel-
based batteries are partially discharged
when purchased, and must be charged
before first use.
Hazards related to batteries
Explosion
A battery explosion is caused by the
misuse or malfunction of a battery, such
as attempting to
recharge a primary
(non-rechargeable)
battery, or short
circuiting a battery.
Corrosion
Many battery chemicals are corrosive,
poisonous, or both. If leakage occurs,
either spontaneously or through accident,
the chemicals released may be dangerous
Environmental pollution
The widespread use of batteries has
created many environmental concerns,
such as toxic metal pollution. Battery
manufacture consumes resources and
often involves hazardous chemicals.
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Fig 1.5 Life cycle
Used batteries also contribute to
electronic waste.
Americans purchase nearly three billion
batteries annually, and about 179,000
tons of those end up in landfills across
the country.
Ingestion
Small button/disk batteries can be
swallowed by young children. While in
the digestive tract the battery's electrical
discharge can burn the tissues and can be
serious enough to lead to death.
Fig 1.6 Electronic waste
PAPER BATTERY
Energy has always been spotlighted. In
the past few years a lot of inventions
have been made in this particular field.
The tiny nuclear batteries that can
provide energy for 10 years, but they use
radioactive elements and are quite
expensive. Few years back some
researchers from Stanford University
started experiments concerning the ways
in which a copier paper could be used as
a battery source. After a long way of
struggle they, recently, concluded that
the idea was right. The batteries made
from a plain copier paper could make for
the future energy storage that is truly
thin.
The anatomy of paper battery is based on
the use of Carbon Nanotubes tiny
cylinders to collect electric charge. The
paper is dipped in lithium containing
solution. The nanotubes will act as
electrodes allowing storage device to
conduct electricity. It’s astounding to
know that all the components of a
conventional battery are integrated in a
single paper structure; hence the
complete mechanism for a battery is
minimized to a size of paper.
One of the many reasons behind
choosing the paper as a medium for
battery is the well-designed structure of
millions of interconnected fibers in it.
These fibers can hold on carbon
nanotubes easily. Also a paper has the
capability to bent or curl.
You can fold it in different shapes
and forms plus it as light as feather.
Output voltage is modest but it could be
increased if we use a stack of papers.
Hence the voltage issues can be easily
controlled without difficulty. Usage of
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paper as a battery will ultimately lead to
weight diminution of batteries many
times as compared to traditional
batteries.
It is said that the paper battery also has
the capability of releasing the energy
quickly. That makes it best utilization for
devices that needs burst of energy,
mostly electric vehicles. Further, the
medical uses are particularly attractive
because they do not contain any toxic
materials.
Fig.2 paper battery
CARBON NANOTUBES
Carbon nanotubes (CNTs) are allotropes
of carbon with a cylindrical
nanostructure. Nanotubes have been
constructed with length-to-diameter ratio
of up to 132,000,000:1, significantly
larger than any other material. These
cylindrical carbon molecules have novel
properties, making them potentially
useful in many applications in
nanotechnology, electronics, optics, and
other fields of materials science, as well
as potential uses in architectural fields.
They may also have applications in the
construction of body armor. They exhibit
extraordinary strength and unique
electrical properties, and are efficient
thermal conductors.
Their name is derived from their size,
since the diameter of a nanotube is on
the order of a few nanometers
(approximately 1/50,000th of the width
of a human hair), while they can be up to
18 centimeters in length (as of 2010).
Nanotubes are categorized as single-
walled nanotubes (SWNTs) and multi-
walled nanotubes (MWNTs).
In theory, metallic nanotubes can carry
an electric current density of 4 × 109
A/cm2 which is more than 1,000 times
greater than metals such as copper,
where for copper interconnects current
densities are limited by electro
migration.
In paper batteries the nanotubes act as
electrodes, allowing the storage devices
to conduct electricity. The battery, which
functions as both a lithium-ion battery
and a super capacitor, can provide a
long, steady power output comparable to
a conventional battery, as well as a super
capacitor’s quick burst of high energy
and while a conventional battery
contains a number of separate
components, the paper battery integrates
all of the battery components in a single
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structure, making it more energy
efficient.
Carbon nanotubes have been
implemented in Nano electromechnical
systems, including mechanical memory
elements(NRAM being developed by
Nantero Inc.)
Fig 3. Carbon nanotubes
FABRICATION OF PAPER
BATTERY
The materials required for the
preparation of paper battery are
a. Copier paper
b. Carbon nano ink
c. Oven
The steps involved in the preparation of
the paper battery are as follows
Step 1: The copier paper is taken.
Step 2: carbon Nano ink which is black
in color is taken. Carbon nano ink is a
solution of nano rods, surface adhesive
agent and ionic salt solutions. Carbon
nano ink is spread on one side of the
paper.
Step 3: the paper is kept inside the oven
at 150C temperature. This evaporates the
water content on the paper. The paper
and the nano rods get attached to each
other.
Step 4: place the multi meter on the sides
of the paper and we can see voltage drop
is generated.
Fig 4. Fabrication process
After drying the paper becomes flexible,
light weight in nature. The paper is
scratched and rolled to protect the nano
rods on paper.
WORKING OF PAPER
BATTERY
The battery produces electricity in the
same way as the conventional lithium-
ion batteries that power so many of
today's gadgets, but all the components
have been incorporated into a
lightweight, flexible sheet of paper.
The devices are formed by combining
cellulose with an infusion of aligned 9
carbon nanotubes. The carbon is what
gives the batteries their black color.
These tiny filaments act like the
electrodes found in a traditional battery,
conducting electricity when the paper
comes into contact with an ionic liquid
solution.
Ionic liquids contain no water, which
means that there is nothing to freeze or
evaporate in extreme environmental
conditions. As a result, paper batteries
can function between -75 and 1500C.
The paper is made conducting material
by dipping in ink. The paper works as a
conductive layer. Two sheets of paper
kept facing inward act like parallel plates
(high energy electrodes). It can store
energy like a super capacitor and it can
discharge bursts of energy because of
large surface area of nano tubes.
Fig.5 working of a paper battery
Chlorine ions flow from the positive
electrode to the negative one, while
electrons travel through the external
circuit, providing current. The paper
electrode stores charge while recharging
in tens of seconds because ions flow
through the thin electrode quickly. In
contrast, lithium batteries take 20
minutes to recharge.
ADVANTAGES
The flexible shape allows
the paper battery to be used small
or irregularly-shaped electronics:
One of the unique features of the paper
battery is that it can be bent to any such
shape or design that the user might have
in mind. The battery can easily squeeze
into tight crevasses and can be cut
multiple times without ruining the
battery's life. For example if a battery is
cut in half, each piece will function,
however, each piece will only contain
1/2 the amount of original power.
Conversely, placing two sheets of paper
battery on top of one-another will double
the power.
The paper battery may
replace conventional batteries
completely:
By layering sheets of this paper, the
battery's voltage and current can be
increased that many times. Since the
main components of the paper battery
are carbon nanotubes and cellulose, the
body structure of the battery is very thin,
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"paper-thin". Thus to maximize even
more power, the sheets of battery paper
can be stacked on top of one another to
give off tremendous power. This can
allow the battery to have a much higher
amount of power for the same size of
storage as a current battery and also be
environmentally friendly at the same
time.
Supply power to an
implanted pacemaker in the
human body by using the
electrolytes in human blood:
An improvement in the techniques used
in the health field can be aided by the
paper battery. Experiments have taken
place showing that batteries can be
energized by the electrolyte emitted from
one's own blood or body sweat. This can
conserve the usage of battery acid and
rely on an environmental friendly
mechanism of fueling battery cells with
the help from our bodies.
The paper battery can be
molded to take the shape of large
objects, like a car door:
As stated earlier, the key characteristics
that make the paper battery very
appealing are that it can be transformed
into any shape or size, it can be cut
multiple times without damaging it, and
it can be fueled through various ways
besides the typical harmful battery acid
that is used in the current day battery.
LIMITATIONS
• Presently, the devices are only a
few inches across and they have to be
scaled up to sheets of newspaper size to
make it commercially viable.
• Carbon nanotubes are very
expensive, and batteries with large
enough power are unlikely to be cost
effective.
• Cutting of trees leading to destroying
of the nature.
APPLICATIONS
Pace makers in heart
(uses blood as electrolyte)
Used as alternate to
conventional batteries in gadgets
Powered smart cards RF
id tags
11
Smart toys, children
sound books
E-cards, greetings, talking
posters
Girls/boys’ apparel
CONCLUSION
We have discussed the various
terminologies, principle of operation of a
battery and recent developments related
to it. The life of a battery is an important
parameter which decides the area of
application of the battery. Increased use
of batteries gives rise to E-waste which
poses great damage to our environment.
In the year 2007 paper battery
was manufactured. The technology is
capable of replacing old bulky batteries.
The paper batteries can further reduce
the weight of the electronic gadgets.
The adaptations to the paper
battery technique in the future could
allow for simply painting the nanotube
ink and active materials onto surfaces
such as walls. These surfaces can
produce energy.
REFERENCES
Thin, Flexible Secondary
Li-Ion Paper Batteries Liangbing
Hu, Hui Wu, Fabio La Mantia,
Yuan Yang, and Yi Cui
Department of Materials Science
and Engineering, Stanford
University, Stanford, California
94305.
David Linden “Handbook
of batteries”
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