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Seminar Report on

PAPER BATTERY

DEPARTMENT OF MECHANICAL ENGINEERING

DECEMBER 2014

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ABSTRACT

In this paper the use of self-rechargeble paper thin film batteries, their performance and

applications has been presented. The Glucose activated paper battery based on glucose

oxidised enzyme using a simple and cheap plastic laminating technology has been

demonstrated. The enzyme and glucose concentration can be optimized to gear up the power

requirement. Ultra fast all polymer paper based batteries are an option with some short

comings yet such as low cycling stabilities and functional discharge rate. Also integration

secondary battery with the paper battery is also shown to improve the power.

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CONTENTS

CHAPTERS PAGE NO

1 INTRODUCTION……………………………………..…………………………6

2 LITERATURE SURVEY....................................................................................7

2.1 Literature Survey............................................................................................7

2.2 Objectives......................................................................................................7

3 PAPER BATTERY………………………………………………………………8

3.1 Glucose activated Laminated Battery……………………………………….9

3.2 Polymer based paper battery……………………………………..…………11

3.3 Li-ion paper battery…………………………………………..…………….13.

4 FABRICATION METHODS ………………………………….………………17..

4.1 Doctor blade process……………………………………….………………17

4.2 Lamination……………………………………………..…………………..18

5 DURABILITY………………………………………………………………….19

6 USE………………………………………………..……………………………20

7 CONCLUSION…………………………………………………………………21

REFERENCES

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LIST OF FIGURES

No. Title Page no.

Figures

3.1.1 Fabrication 10

3.1.2 Glucose-activated laminated battery 11

3.2.1 Cell voltage vs time graph, 12

3.2.2 Charge capacity vs charge current 12

3.3.1 Fabrication of li ion battery on paper 14

3.3.2 Cycling performance of LTO nanopowder (C/5, 0.063ma)

half cells 15

3.3.3 Li ion paper battery energy increased through stacking

16

4.1 Doctor blade 17

4.2 Roll laminator 18

Tables

3 Influence of electrode thickness in electrical

characteristics of devices

9

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CHAPTER 1

INTRODUCTION

Paper can turn quite an interesting material to produce very cheap disposable electronic

devices with the great advantage of being environment friendly. The possibility to produce

large scale low cost disposable electronic devices has been opened like never before with

revolution of paper transistors, transparent thin film transistors based on semiconductor

oxides and paper memory. The common material of all these recent electronic devices is

cellulose fibre-based paper as active material in opposition to other Ink-jet printed active

matrix display. This emphasises the need of the use of cheap yet reliable material for the

fabrication of electronic devices. Many modifications of the prime model have been brought

out from time to time to keep up with the challenges and demands of the present world.

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CHAPTER 2

LITERATURE SURVEY

2.1 LITERATURE SURVEY

The literature survey conducted are as follows

1.Gustav Nystro¨M, Aamir Razaq, Maria Strømme, Leif Nyholm, AND Albert Mihranyan

studied ultrafast all-polymer paper-based batteries. In the process they tried to replace the

metal/metal oxide with polymer. The preparation of novel redox polymer and electronically

conducting polymer-based electrode materials is essential.Conducting polymers are

particularly interesting materials as devices based on these materials could be used as

adaptable energy storage devices due to their inherent fast redox switching, high

conductivity, mechanical flexibility, low weight and possibility to be integrated into existing

production processes.

2. Liangbing Hu, Hui Wu, Fabio La Mantia, Yuan Yang, and Yi Cui investigated about Thin

Flexible Secondary Li-Ion Paper Batteries”. They tried to integrate Li-ion battery onto a

paper battery. They integrated all of the components of a Li-ion battery into a single sheet of

paper with a simple lamination process. Due to the intrinsic porous structure of the paper, it

functions effectively as both a separator with lower impedance than commercial separators

and has good cyclability.

3. Ki Bang Lee studied about the Urine Activated Paper Batteries. A simple and cheap

fabrication process for the paper batteries, compatible to the existing plastic laminating

technologies or plastic moulding techniques was developed by him. A paper battery is tested

and it can deliver a power greater than 1.5mw.

2.2 OBJECTIVES

To study the following:

1. The use of self-rechargeable paper thin film batteries, their performance and

application.

2. The Glucose activated paper battery based on glucose oxidised enzyme.

3. Ultra fast all polymer paper based batteries.

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CHAPTER 3

PAPER BATTERY

A paper battery is a flexible, ultra-thin energy storage and production device formed by

combining carbon nanotube with a conventional sheet of cellulose-based paper. A paper

battery acts as both a high-energy battery and supercapacitor , 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.

Paper batteries may be folded, cut or otherwise shaped for different applications without any

loss of integrity or efficiency . Cutting one in half halves its energy production. Stacking

them multiplies power output. Early prototypes of the device are able to produce 2.5 volt s of

electricity from a sample the size of a postage stamp.

The devices are formed by combining cellulose with an infusion of aligned carbon nanotubes

that are each approximately one millionth of a centimetre thick. The carbon is what gives the

batteries their black colour.

Cellulose based paper is a natural abundant material, biodegradable, light, and recyclable

with a well-known consolidated manufacturing process. Here, we expect to contribute to the

first step of an incoming disruptive concept related to the production of self-sustained paper

electronic systems where the power supply is integrated in the electronic circuits to fabricate

fully self sustained disposable, flexible, low cost and low electrical consumption systems

such as tags, games or displays.

In achieving such goal we have fabricated batteries using commercial paper as electrolyte and

physical support of thin film electrodes. A thin film layer of a metal or metal oxide is

deposited in one side of a commercial paper sheet while in the opposite face a metal or metal

oxide with opposite electrochemical potential is also deposited. The simplest structure

produced is Cu/paper/Al but other structures such as Al paper WO3/ TCO were also tested,

leading to batteries with open circuit voltages varying between 0.50 and 1.10 V. On the other

hand, the short current density is highly dependent on the relative humidity (RH), whose

presence is important to recharge the battery. The set of batteries characterized show stable

performance after being tested by more than 115 hours, under standard atmospheric

conditions [room temperature, RT (22 C) and 60% air humidity, RH].

The thicknesses of the metal electrodes varied between 100 and 500 nm. The Al/paper/Cu

thin batteries studied involved the use of three different classes of paper: commercial copy

white paper (WP: 0.68 g/cm , 0.118 mm thick); recycled paper (RP:0.70 g/cm , 0.115 mm

thick); tracing paper (TP: 0.58 g/cm ,0.065 mm thick). The role of the type of paper and

electrodes thickness on the electrical parameters of the battery, such as the Voc and Jsc are

indicated in Table I

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The thickness of the metal layer does not play a remarkable role on electrical characteristics

of the batteries. Considering that the tracing paper is less dense and thinner than white and

recycled paper, the difference on the current density observed can be related to ions

recombination either due to impurities inside the foam/mesh-like paper structure or charge

annihilation by vacant sites associated to the surface of the paper fibers, existing in thicker

papers. Other possible explanation is that the adsorption of water vapor is favored in less

dense paper. We conclude that this type of battery is a mixture of a secondary battery and a

fuel cell where the fuel is the water vapor and so its application requires environment with

40%.

Batteries able to supply a Voc=.70V and Jsc > 100 nA/cm at Relative humidity=60% were

fabricated using respectively as anode and cathode thin metal films of Al and Cu as thin as

100 nm.

3.1 Glucose activated Laminated Battery

Now lets consider the case of glucose activated laminated, which is the modification of the

previous work.

Fabrication of above is shown below.

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Figure2.1.1: Fabrication

Fabrication process for the paper battery: the whole assembly consisting of copper, enzyme-

doped special paper, Magnesium sandwiched between two laminating plastics is bound

together while passing through rollers.

In order to obtain a glucose-activated battery, we modify the urine-activated paper batteries

that include Copper Chloride (CuC1) as the cathode in paper. Instead of Copper Chloride in

the paper, we tried to use the glucose-oxidase (GOD) for the glucose-activated battery.

Fig. 1 shows the detailed lamination process for the fabrication of battery. This whole stack

consisting of the magnesium, enzyme-doped special paper, copper sandwiched between two

plastic films into a roller which bounds the whole assembly together is laminated into a paper

battery. A 0.10mm-thick lower transparent plastic film with an adhesive (Fig. la) is used as a

substrate to fabricate the battery. A 0.2”-thick copper layer are deposited (or taped) and

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patterned for the positive electrode (Fig. la). After taping a 0.2”-thick aluminium layer (Fig. 1

b), the aluminium layer is patterned to provide electrical connection and electrodes. In Figs.

l(c) and (d), 0.2”-thick glucose-oxidase enzyme doped paper and magnesium layer are

stacked on the copper layer. After placing the upper transparent plastic film with an adhesive

layer on the stack (Fig. le), the whole layers are laminated into the micro-battery while

passing through the heating rollers. Glucose supply slit and air exhalation slit are made on the

upper plastic film in Fig. l(e).

Fig. 2 shows the schematic diagram of a glucose-activated laminated battery consisting of a

glucose-oxidase coated paper sandwiched between magnesium and copper layers.

FIGURE 2.1.2 Glucose-activated laminated battery

We can conclude that higher enzyme concentration results in faster oxidation of glucose, and

hence better voltage and power are achieved. Thus we prefer for that. The first glucose-

activated battery fabricated by a plastic lamination technology has been demonstrated for

ondemand bio-applications and disposal usages. Basic concept of the battery is presented and

the prototype battery can be fabricated by simple lamination processes using thin plastic film.

3.2 Polymer based paper battery

Now we try to replace the metal/metal oxide with polymer. In this process, the preparation of

novel redox polymer and electronically conducting polymer-based electrode materials is

essential. While it has recently been shown that it is possible to manufacture redox polymer

based electrodes and batteries with high-capacities and very good cycling performances, the

corresponding development within the field of electronically conducting polymers is

ongoing. Conducting polymers are particularly interesting materials as devices based on these

materials could be used as adaptable energy storage devices due to their inherent fast redox

switching, high conductivity, mechanical flexibility, low weight and possibility to be

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integrated into existing production processes. While conductive polymers are more

environmentally friendly and cost-efficient than most metal containing electrode materials,

the insufficient cycle stabilities and the high self-discharge rates have so far been limiting

their applicability in commercial battery systems.

In the past, several attempts have been made to produce energy storage devices consisting of

entirely non-metal components. One way to improve the performance of nonmetal-based

energy storage devices would be to use composite electrode materials of conductive

polymers, for example, polypyrrole (PPy).

Figure 3.2.1 Cell voltage vs time graph, Figure 3.2.2 charge capacity vs charge current

In Figure 1a, the galvanostatic charge-discharge curves are shown for the battery based on the

use of different charge and discharge currents. In these experiments, the cell was cycled for

10 cycles at each current, and the results of the seventh of these cycles are depicted in the

figure. To avoid problems due to overoxidation27 of the PPy coating, the charging of the cell

was interrupted at a voltage just below the potential where this was found to take place for

the different currents.The results in Figure 1a clearly show that the PPy coatings could be

reversibly oxidized and reduced continuously even at very high rates. It can thus be seen that

it was possible to decrease the charging time from 8 min at 10 mA to only 11.3 s at a current

of 320 mA . As these currents correspond to rates of 7.5 and 320 C (i.e., charge/discharge

within 1/7.5 and 1/320 of an hour), respectively, the results are in excellent agreement with

the expected behaviour for an electrode material composed of a thin electro active layer on a

large surface area substrate.

Figure 1b shows the charge capacities calculated from the charge curves in Figure 2a, after

normalizing with respect to the total weight of the composite material. It is seen that 72% of

the electrode capacity obtained with a current of 10 mA was maintained when increasing the

current to 320 mA.This demonstrates the outstanding ability of the material to undergo rapid

oxidation and reduction. For comparison, most currently employed commercial rechargeable

batteries generally require at least an hour to completely recharge because hastened charging

increases the demands on the robustness of electrode reactions and shortens the cycling

lifetime of the electrode.28 As is seen in Figure 2b, the charge capacities obtained at 10 and

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320 mA were about 33 and 25 mAh g-1.This means that the capacity for this particular cell

containing 37.5 mg conductive paper was approximately 1.2 and 0.9 mAh, respectively.

Thus,the presented PPy-cellulose composite material is mechanically robust, lightweight, and

flexible. It can be molded into various shapes and its thin sheets can be rolled to make very

compact energy storage devices. The widespread availability of cellulose and the

straightforward manufacturing of the composite are key factors for producing cost-efficient

and fully recyclable paper-based batteries on a large industrial scale. Whereas the system

described herein is limited in terms of the delivered cell potential, at least when compared

with Li-ion batteries, the present battery holds great promise for applications in areas where

Li-ion batteries are difficult to use, for example, in inexpensive large-scale devices or flexible

energy storage devices to be integrated into textiles or packaging materials. The present

paper-based battery system has also been shown to be compatible with very high charging

rates. Together with the good cycling stability this makes the PPy-cellulose composite highly

suitable for inclusion in future high-performance energy storage systems.

3.3 Li-ion paper battery

Secondary Li-ion batteries are key components in portable electronics due to their high

powerand energy density and long cycle life. So we are trying to integrate Li-ion battery onto

a paper battery.

We integrated all of the components of a Li-ion battery into a single sheet of paper with a

simple lamination process. Free-standing, lightweight CNT thin films (0.2 mg/cm2) were

used as current collectors for both the anode and cathode and were integrated with battery

electrode materials through a simple coating and peeling process. The double layer films

were laminated onto commercial paper, and the paper functions as both the mechanical

support and Li-ion battery membrane Due to the intrinsic porous structure of the paper, it

functions effectively as both a separator with lower impedance than commercial separators

and has good cyclability (no degradation of Li-ion battery after 300 cycles of recharging).

After polymer sealing, the secondary Li-ion battery is thin (300 um), mechanically flexible,

and has a high energy density. Such flexible secondary batteries will meet many application

needs in applications such as interactive packaging, radio frequency sensing, and electronic

paper. The CNT ink was applied to the SS substrate with a doctor blade method. A dried film

with a thickness of 2.0 um was formed after drying the CNT ink on the SS substrate at 80 °C

for 5 min. Slurries of battery materials, Li4Ti5O12 (LTO) and LiCoO2 (LCO) (Predmaterials

& LICO), were prepared. The battery slurries were applied to CNT/SS with the same doctor

blade method. The slurries were dried at 100 °C for 0.5 h. The battery electrode material on

the CNT film forms a double layer film, where CNT films function as the current collectors.

As shown in Figure 2a, the double layer LCO/CNT or LTO/CNT film was lifted off by

immersing the SS in DI water followed by peeling with tweezers. Figure 2b shows a

LTO/CNT film with a size of 7.5 cm *12.5 cm on a SS substrate (left) being peeled off in

water (middle) and in a free-standing form (right). Previously, CNT thin films have been

coated mainly on plastic substrate for use as transparent electrodes in various device

applications, including solar cells and light emitting diodes. In this study, we found that

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CNTs have weaker interaction with metal substrates when compared with plastic or paper

substrates, which allows us to fabricate free-standing films with integrated current collector

and battery electrodes. The double layer films obtained with this method are lightweight, with

0.2 mg/cm2 CNT and 2~10 mg/cm2 electrode material. The free-standing double layer film

shows a low sheet resistance (~5 Ohm/sq) and excellent flexibility, without any change in

morphology or conductivity after bending down to 6 mm (Mandrel). Due to the excellent

mechanical integrity of the double layer film and the loose interaction between the CNT film

and SS, peeling off the double layer film from the SS is highly reproducible. After integrating

the battery electrode materials on the lightweight CNT current collectors, a lamination

process was used to fabricate the Li-ion paper batteries on paper. A solution of

polyvinylidene fluoride (PVDF) polymer was coated on the paper substrate with an effective

thickness of 10 um. The wet PVDF functions as a glue to stick the double layer films on

paper. As shown in Figure 2c, the double layer films were laminated on the paper while the

PVDF/ NMP was still wet. During this process, a metal rod rolls over the films to remove air

bubbles trapped between films and the paper separator. After laminating LTO/CNT on one

side of the paper, the same process was used to put LCO/CNT on the opposite side of the

paper to complete the Li-ion battery fabrication. Figure 3.3.3 shows the scheme and a final

device of the Li-ion paper battery prior to encapsulation and cell testing.

Figure 3.3.1 Fabrication of li ion battery on paper

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Although a paper-like membrane has been used as the separator for other energy storage

systems including supercapacitors, it is the first demonstration of the use of commercial paper

in Li-ion batteries, where paper is used as both separator and mechanical support. Xerox

paper lacks microsize holes, which makes it an excellent separator for Li-ion batteries with

the laminated electrode films. We tried coating battery electrode materials with the same

slurries directly onto either side of Xerox paper, and we found occasional shorting of the

device due to the leakage of battery electrode materials through paper. The lamination

process provides an efficient approach for solving the leakage problem by using Xerox paper

as a separator because the battery electrode forms a solid film and is integrated with the CNT

film. CNT thin films form continuous mechanical supports and serve as electrical current

collectors for the electrodes. The sheet resistance of the CNT thin film can be further

decreased with acid doping such as with HNO3 or SOCl2.

To evaluate the performance of paper as an effective separator membrane for Li-ion batteries,

its stability in the electrolyte and the effect of the impurities. cells were fabricated with CNT

films as cathodes, Li-metal as anodes, and Xerox paper as the separators. Cells were

fabricated with CNT films as cathodes, Li-metal as anodes, and Xerox paper as the

separators. paper shows low resistivity in the electrolyte.

Figure3.3.2 Cycling performance of LTO nanopowder (C/5, 0.063ma) half cells

To test the feasibility of using Xerox paper as the separator in Li-ion batteries with the

lamination process, half cells were made with CNT/LTO or CNT/LCO with lithium foil as a

counter electrode. Voltage profiles closely match those with metal current collectors and no

apparent voltage drop was observed.

Full cells with integrated current collectors and battery electrodes onto a single sheet or paper

are fabricated with the lamination process. The laminated Li-ion paper battery has the

structure illustrated in Figure 3.3.3. After the CNT/LCO and CNT/LTO films were laminated

onto the two sides of Xerox paper, the whole device was sealed. The Li-ion paper battery

is thin.

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Due to the small thickness and the great flexibilities of current collectors using CNT thin

films, the whole device shows excellent flexibility. No failure was observed for the paper

battery after manually bending the device down to 6 mm for 50 times. The self-discharge

performance could be further improved through device fabrication process modifications

such as better sealing, longer vacuum baking times, and lower moisture levels by using

standard dry rooms.

Figure 3.3.3 Li ion paper battery energy increased through stacking

The CNT weight in our device is less, therefore, the CNT cost is negligible. One method for

increasing the total energy for the Li-ion paper battery is through stacking layer upon layer,

as in Figure 4, where conductive CNT films function as current collectors, and extended

metal strips at the edge serve as connections to the external circuit.

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CHAPTER 4

FABRICATION METHODS

Doctor blade and lamination process were termed quite often. Now lets discuss about the two

process:

4.1 DOCTOR BLADE PROCESS

Generic term for any steel, rubber, plastic, or other type of blade used to apply or remove a

liquid substance from another surface, such as those blades used in coating paper. The term

"doctor blade" is believed to be derived from the name of a blade used in conjunction with

ductor rolls on letterpress presses. The term "ductor blade" eventually mutated into the term

"doctor blade."

Figure 4.1: Doctor Blade

The doctor blade is fixed firmly in place by a doctor blade assembly, the amount of blade

protruding from the holder being known as the blade extension—generally recommended to

be K:H inch. It is set at certain optimum angles to ensure minimal blade and/or cylinder wear.

The angle at which the blade contacts the cylinder (called the contact angle) is generally

55:65º, with 60º being most manufacturers' specified contact angle. The angle can be varied

to correct various cylinder defects and/or inking problems. The contact angle also affects the

distance between the blade and the nip between the gravure cylinder and the impression

roller. This distance needs to be small enough to prevent drying-in, the undesirable drying of

ink in the gravure cylinder cells. Many doctor blades oscillate across the width of the cylinder

as a means of preventing cylinder wear and to remove solid bits of debris that can collect on

the surface of the cylinder of the rear of the blade itself. The force or pressure with which the

blade contacts the cylinder should be as minimal as possible, or should wipe the cylinder

effectively but not contribute to blade and/or cylinder wear. (The process of setting the

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contact angle and blade contact pressure is known as running in or toning in.) A related

consideration is the unavoidable deflection of the blade during the print run, or, in other

words, a slight curvature of the blade caused by the rotating cylinder. The contact angle and

blade pressure should take into account deflection. The edge of the blade itself comes in a

variety of configurations, either pre-honed by the manufacturer or honed in-house by the

printer. Regardless of the configuration, the important considerations are effective wiping and

the minimization of wear. Surface roughness of the cylinder is important for doctor blade

lubrication. Gravure cylinders that are too smooth will increase doctor blade wear and

cylinder damage. On some packaging presses, scavenger marks are deliberately etched into

non-image areas corresponding to non-printing regions of the substrate (and which can be

removed during finishing operations, such as trimming) to facilitate the removal of particles

of ink or other debris from beneath the doctor blade.

4.2 LAMINATION

Lamination is the technique of manufacturing a material in multiple layers, so that the

composite material achieves improved strength, stability, appearance or other properties from

the use of differing materials. A laminate is usually permanently assembled by heat, pressure,

welding, or adhesives.

Roll laminator is used as high speed laminating machine. Lamination supplies for these

laminators should be in roller form. This lamination process is very cost effective and time

for making laminate is less. Bulk lamination is done by roll laminating machines.

Laminating film passes over a big roller. Roll

laminators can be divided into two types

based on lamination process.

Hot roll laminator

Cold roll laminator

Thermal laminating films are used in hot roll

laminator. These lamination supplies have one

side heat sensitive. This film is passed over

heated roll and laminating adhesive starts

melting. In the next step film with print goes

between nip rolls and due to pressure and

temperature it laminates. Figure 4.2 Roll Laminator

Cold roll laminator don't use heat in lamination process. Laminating is done due to the effect

of pressure. Film has one side with pressure sensitive adhesive. We use cold roll laminators

where media have some heat sensitive characteristics. Laminate can be given different look

like matte, glossy or satin finish by using various lamination supplies.

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CHAPTER 5

DURABILITY

The use of carbon nanotubes gives the paper battery extreme flexibility, the sheets can

be rolled, twisted, folded or cut into numerous shapes with no loss of integrity or

efficiency, or stacked, like printer paper(or a voltaic pile),to boost total output. As well,

they can be made in a variety of sizes, from postage stamp to broadsheet. It is essentially

a regular piece of paper, but it is made in a very intelligent way, ”said Linhardt, ”We are

not putting pieces together-it is a single, integrated device,” he said. “The components

are molecularly attached to each other .The carbon nanotube is embedded in the paper,

and the electrolyte is soaked into the paper. The end result is a device that looks, feels,

and weighs the same as paper.”

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CHAPTER 6

USE

The paper-like quality of the battery combined with the structure of the nanotubes embedded

within gives them their light weight and low cost, making them attractive for portable

electronics, aircraft, automobiles, and toys, while their ability to use electrolytes in blood make

them potentially useful for medical devices such as pacemakers. The medical uses are

particularly attractive because they do not contain any toxic materials and can be biodegradable;

a major drawback of chemical cells. However, Professor Sperling cautions that commercial

applications may be a long way away, because nanotubes are still relatively expensive to

fabricate. Currently they are making devices a few inches in size. In order to be commercially

viable, they would like to be able to make them newspaper size; a size which, taken all together

would be powerful enough to power a car.

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CHAPTER 7

CONCLUSION

The Glucose activated battery fabricated by a plastic lamination technology has been

demonstrated for on demand bio-application and disposal usages. Many different techniques

are available to harvest raw energy to power wearable electronics, but the amount of raw

energy and surface area or net mass that the wearable device permits limit the power yield.

Thus all the different aspects of paper based battery fabrication technology with a

modification like glucose based paper battery, polymer based paper battery, Li based paper

battery have been studied.

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REFERENCE

1. Gustav Nystro¨m, Aamir Razaq, Maria Strømme, Leif Nyholm, and Albert

Mihranyan; Nanotechnology and Functional Materials, Department of Engineering

Sciences, The Ångstro¨m Laboratory, Uppsala University, Box 534, 751 21 Uppsala, Sweden,

and Department of Materials Chemistry, The Ångstro¨m Laboratory, Uppsala University,

Box 538, 751 21 Uppsala, Sweden: “Ultrafast All-Polymer Paper-Based Batteries”.

2. Ki Bang Lee, Institute Of Bioengineering And Nanotechnology, “Urine Activated Paper

Batteries”

3. Liangbing Hu, Hui Wu, Fabio La Mantia, Yuan Yang, and Yi Cui; Department of

Materials Science and Engineering, Stanford University, Stanford, California 94305. †These

authors contributed equally to this work: “Thin, Flexible Secondary Li-Ion Paper

Batteries”.

4. www.wikipedia.org

5. www.pediain.com

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QUESTIONS AND ANSWERS

1. What is the width of the nanotube used?

The width of the nanotube is 10-40 nm.

2. What is Voc ?

Voc stands for open circuit voltage.

3. What is open circuit voltage ?

Open circuit voltage is the voltage obtained when the load applied is zero.

4. Whether paper battery can be used in automobiles?

If paper battery is of the size of a newspaper, then it can be used in a car.

5. What is LTO ?

Li4Ti5O12

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