26
CHAPTER – 1 INTRODUCTION TO PAPER BATTERY 1.1 INTRODUCTION TO ORDINARY BATTERY Ordinary paper could one day be used as a lightweight battery to power the devices that are now enabling the printed word to be eclipsed by e-mail, e-books an online news. Scientists at Stanford University in California reported on Monday they have successfully turned paper coated with ink made of silver and carbon nano materials into a "paper battery" that holds promise for new types of lightweight, high-performance energy storage. The same feature that helps ink adhere to paper allows it to hold onto the single-walled carbon nano tubes and silver nano wire films. Earlier research found that silicon nano wires could be used to make batteries 10 times as powerful as lithium ion batteries now used to power devices such as laptop computers. KMCET,DVK 1 DEPT. OF ECE

Naveen Doc

Embed Size (px)

DESCRIPTION

hi

Citation preview

Page 1: Naveen Doc

CHAPTER – 1

INTRODUCTION TO PAPER BATTERY

1.1 INTRODUCTION TO ORDINARY BATTERY

Ordinary paper could one day be used as a lightweight battery to power the devices that

are now enabling the printed word to be eclipsed by e-mail, e-books an online news. Scientists at

Stanford University in California reported on Monday they have successfully turned paper

coated with ink made of silver and carbon nano materials into a "paper battery" that holds

promise for new types of lightweight, high-performance energy storage.

The same feature that helps ink adhere to paper allows it to hold onto the single-walled carbon

nano tubes and silver nano wire films. Earlier research found that silicon nano wires could be

used to make batteries 10 times as powerful as lithium ion batteries now used to power devices

such as laptop computers.

Figure 1.1.1 Ordinary battery

KMCET,DVK 1 DEPT. OF ECE

Page 2: Naveen Doc

`"Taking advantage of the mature paper technology, low cost, light and high performance

energy-storage are realized by using conductive paper as current collectors and electrodes," the

scientists said in research published in the Proceedings of the National Academy of Sciences.

This type of battery could be useful in powering electric or hybrid vehicles, would make

electronics lighter weight and longer lasting, and might even lead someday to paper electronics,

the scientists said. Battery weight and life have been an obstacle to commercial viability of

electric-powered cars and trucks."Society really needs a low-cost, high performance energy

storage device, such as batteries and simple super capacitors," Stanford assistant professor of

materials science and engineering and paper co-author Yi Cui said.

Cui said in an e-mail that in addition to being useful for portable electronics and

wearable electronics, "Our paper super capacitors can be used for all kinds of applications that

require instant high power.”

Figure 1.1.2 Conventional battery

"Since our paper batteries and super capacitors can be very low cost, they are also good

for grid-connected energy storage," he said. Peidong Yang, professor of chemistry at the

KMCET,DVK 2 DEPT. OF ECE

Page 3: Naveen Doc

University of California. Berkeley, said the technology could be commercialized within a short

time.

1.2 INTRODUCTION OF 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 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.

Figure 1.2.1 carbon nanotubes

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.

KMCET,DVK 3 DEPT. OF ECE

Page 4: Naveen Doc

Figure 1.2.2 paper battery

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

nanotubes that are each approximately one millionth of a centimeter thick. The carbon is what

gives the batteries their black color. These tiny filaments act like the electrode s 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

150 degrees Celsius.

One method of manufacture, developed by scientists at Rensselaer Polytechnic Institute

and MIT, begins with growing the nanotubes on a silicon substrate and then impregnating the

gaps in the matrix with cellulose. Once the matrix has dried, the material can be peeled off of the

substrate, exposing one end of the carbon nanotubes to act as an electrode .

Figure 1.2.3 paper battery

When two sheets are combined, with the cellulose sides facing inwards, a super capacitor is

formed that can be activated by the addition of the ionic liquid. This liquid acts as an electrolyte

and may include salt-laden solutions like human blood, sweat or urine. The high cellulose

KMCET,DVK 4 DEPT. OF ECE

Page 5: Naveen Doc

content (over 90%) and lack of toxic chemicals in paper batteries makes the device both

biocompatible and environmentally friendly, especially when compared to the traditional lithium

ion battery used in many present-day electronic devices and laptops.

Widespread commercial deployment of paper batteries will rely on the development of

more inexpensive manufacturing techniques for carbon nanotubes. As a result of the potentially

transformative applications in electronics, aerospace, hybrid vehicles and medical science,

however, numerous companies and organizations are pursuing the development of paper

batteries. In addition to the developments announced in 2007 at RPI and MIT, researchers in

Singapore announced that they had developed a paper battery powered by ionic solutions in

2005. NEC has also invested in R & D into paper batteries for potential applications in its

electronic devices. Specialized paper batteries could act as power sources for any number of

devices implanted in humans and animals, including RFID tags, cosmetics, drug-delivery

systems and pacemakers.

A capacitor introduced into an organism could be implanted fully dry and then be gradually

exposed to bodily fluids over time to generate voltage. Paper batteries are also biodegradable, a

need only partially addressed by current e-cycling and other electronics disposal methods

increasingly advocated for by the green computing movement.

KMCET,DVK 5 DEPT. OF ECE

Page 6: Naveen Doc

CHAPTER – 2

MANUFACTURING OF PAPER BATTERY

2.1 MANUFACTURING OF CARBON NANOTUBES

One method of manufacture, developed by scientists at Rensselaer Polytechnic Institute

and MIT, begins with growing the nano tubes on a silicon substrate and then impregnating the

gaps in the matrix with cellulose. Once the matrix has dried, the material can be peeled off of the

substrate, exposing one end of the carbon nano tubes to act as an electrode .

Figure 2.1 paper battery

When two sheets are combined, with the cellulose sides facing inwards, a super capacitor

is formed that can be activated by the addition of the ionic liquid. This liquid acts as an

electrolyte and may include salt-laden solutions like human blood, sweat or urine. The high

cellulose content (over 90%) and lack of toxic chemicals in paper batteries makes the device

both biocompatible and environmentally friendly, especially when compared to the traditional

lithium ion battery used in many present-day electronic devices and laptops.

Specialized paper batteries could act as power sources for any number of devices

implanted in humans and animals, including RFID tags, cosmetics,

KMCET,DVK 6 DEPT. OF ECE

Page 7: Naveen Doc

drug-delivery systems and pacemakers. A capacitor introduced into an organism could be

implanted fully dry and then be gradually exposed to bodily fluids over time to generate voltage.

Paper batteries are also biodegradable, a need only partially addressed by current e-cycling and

other electronics disposal methods increasingly advocated for by the green computing

movement.

2.2 DEVELOPMENT

The creation of this unique nano composite paper drew from a diverse pool of disciplines,

requiring expertise in materials science, energy storage, and chemistry. The researchers used

ionic liquid, essentially a liquid salt, as the battery’s electrolyte. The use of ionic liquid, which

contains no water, means there’s nothing in the batteries to freeze or evaporate. “This lack of

water allows the paper energy storage devices to withstand extreme temperatures,” Kumar said.

It gives the battery the ability to function in temperatures up to 300 degrees Fahrenheit and down

to 100 below zero. The use of ionic liquid also makes the battery extremely biocompatible; the

team printed paper batteries without adding any electrolytes, and demonstrated that naturally

occurring electrolytes in human sweat, blood, and urine can be used to activate the battery

device.

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

with a well-known consolidated manufacturing process. These attributes turn paper a quite

interesting material to produce very cheap disposable electronic devices with the great advantage

of being environmental friendly. The recent (r) evolution of thin-film electronic devices such as

paper transistors [1], transparent thin-film transistors based on semiconductor oxides [2], and

paper memory [3], open the possibility to produce low cost disposable electronics in large scale.

Common to all these advances is the use of cellulose fiber-based paper as an active material in

opposition to other ink-jet printed active-matrix display [4] and thin-film transistors [5] reports

where paper acts only as a passive element (substrate). Batteries in which a paper matrix is

incorporated with carbon nanotubes [6], or biofluid - and water-activated batteries with a filter

paper [7] have been reported, but it is not known a work where the paper itself is the core of the

device performance.

KMCET,DVK 7 DEPT. OF ECE

Page 8: Naveen Doc

Figure 2.2 development of paper battery

With the present work, 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 WO 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

KMCET,DVK 8 DEPT. OF ECE

Page 9: Naveen Doc

conditions [room temperature, RT (22 C) and 60% air humidity, RH]. In this work we also

present as a proof of concept a paper transistor in which the gate ON/OFF state is controlled by a

non-encapsulated 3 V integrated paper battery.

KMCET,DVK 9 DEPT. OF ECE

Page 10: Naveen Doc

CHAPTER – 3

EXPERIMENTAL DETAILS

3.1 EXPERIMENTAL DETAILS

The paper batteries produced have the Al/paper/Cu structure, where the metal layers were

produced by thermal evaporation at RT. The thicknesses of the metal elect rodes varied between

100 and 500 nm. The electrical characteristics of the batteries were obtained through I–V curves

and also by sweep voltammetry using scanning speed of 25 mV/s and the electrodes area of 1 cm

. A Keithley 617 Programmable Electrometer with a National Instruments GPIB acquisition

board were used to determine the I–V characteristics.

Figure 3.1 Dependence of temperature on discharge

capacity

KMCET,DVK 10 DEPT. OF ECE

Page 11: Naveen Doc

The cyclic voltammetry was performed with a potenciostat Gamry Instruments—Ref. 600

in a two-electrode configuration. The electrical performances of the batteries were determined by

monitoring the current of the battery under variable RH conditions. The surface analysis of the

paper and paper batteries was performed by S-4100 Hitachi scanning electron microscopy

(SEM), with a 40 tilt angle. The electrical properties of the paper transistor controlled by the

paper battery were monitored with an Agilent 4155C semiconductor parameter analyzer and a

Cascade M150 microprobe station.

Figure 3.2 Typical series

connection method

KMCET,DVK 11 DEPT. OF ECE

Page 12: Naveen Doc

CHAPTER – 4

RESULTS AND DISCUSSION

4.1 RESULTS AND DISCUSSION

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 TP is made of

long pine fibers and according to FRX (X-ray fluorescence) mainly Al2 O3 (24%), SiO2 (37%),

SO2 (15%), CaO (9%), and Na2 O (4%). 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, for

RH of 50%–60%, using metal electrodes with different thicknesses (t1=100 nm; tot2=250

nm;t3=500 nm). Jsc for WP is ~ 40%–50% lower than of TP, and RP is one order of magnitude

lower than WP. Consequently, the Voc is reduced by merely a ~ 0.1 V when moving from WP to

RP only for thickness (t1=100 nm) while it increases for t2 and t3.

KMCET,DVK 12 DEPT. OF ECE

Page 13: Naveen Doc

Figure 4.1 Photograph of the paper batteries with a

sketch of the cross section

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

characteristics of the batteries. The results show that it is enough to guarantee the step coverage

of the randomly dispersed fibers by metal or metal–oxide thin films to allow the carriers to find a

continuous pathway without the inhibition of water vapor absorption by the paper fibers.

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. Fig. 4.1 shows a photograph and a sketch of a paper battery analysis it contains

with an Al anode while the cathode is Cu, whose difference in work functions influences the set

of chemical reactions that take place within the paper mesh structure.

produced in The paper SEM image of Fig. 4.2 is the surface morphology of tracing paper

used. There, large (50 m). This mesh-like structure favors OHx absorption on the surface of the

fibers, in line with data depicted in Table 4.1, where the batteriesproduced in WP show currents

oneorderof magnitude lower than the one TP.

KMCET,DVK 13 DEPT. OF ECE

Page 14: Naveen Doc

figure 4.2 SEM image of the paper surface.

KMCET,DVK 14 DEPT. OF ECE

Page 15: Naveen Doc

Figure 4.3 SEM image of the anode (Al) surface

For RP, two orders of magnitude difference in is observed. Voc is reduced by 0.1–0.2 V

when moving from WP to RP as electrolyte. The paper battery prototype used is non-

encapsulated and so, its electrical performance is influenced by the atmospheric constituents.

This behavior was confirmed by measuring the current of one cell in vacuum and under

atmospheric pressure [8]. The results demonstrated a reduction of one order of magnitude in Jsc

value after vacuum reaching 10 Pa. These results were reproducible after performing several

tests. We attributed this behavior to the incorporation of OH radicals from adsorbed water and its

contribution to the enhancement of current through the typical reactions Of

2H2 OO2+ 4H+ +4e- and/or

4OHO2+2 H2 O+4e

- and subsequent reactions with the paper fibers constituents (cellulose and ions). This was

confirmed by measuring the current variation as RH changes.

The graph of Fig. 4.4 shows the short circuit-current density variation as RH increases for

TP. A variation of about three orders of magnitude is observed when RH changes from 60% to

85%, and it is reversible, meaning that no battery damage is verified. 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 RH>40 % or proper encapsulation with controlled

humidity via holes through which we can allow the battery to breathe.

Table 4.1 Influence of the electrodes thickness in the

electrical characteristics of devices

KMCET,DVK 15 DEPT. OF ECE

Page 16: Naveen Doc

This is the case in applications with typically high RH, as in the food industry, where

these batteries could be used to turn electronic tags autosustained. From the data taken, each

battery element is able to supply a power from 75 nW/cm to 350 W/cm , depending on RH. The

desired voltage and power output can be achieved by integrating in series and in parallel the

battery elements produced.

In the present case, a prototype battery able to supply a 3 V was produced to actuate the

gate of a paper transistor working in the depletion mode. Fig. 4.4 shows a photograph of the

prototype made of 10 cells (with only 8 cells connected in series) and the graph of the drain

current of the paper transistor when the paper battery is connected to the gate ( 3 V) or

disconnected (0 V).The connection/disconnection were repeated during 400 s in intervals of 25 s

and the current was monitored continuously.

The results clearly show the sustainability of the paper battery in powering the gate of the

transistor and how the results are reproducible. The drain current of the paper transistor at 0 V is

2 10 A and at 3V is 10 A, similar to the values obtained when measuring the transfer

characteristics of the same devices with a semiconductor analyzer [1].

CHAPTER – 5

APPLICATION AND USES OF PAPER BATTERY

5.1 IN COSMETICS

Anti-aging and wrinkles

Dark spots / Discoloration

Skin lightening / Whitening

Firming and lifting

KMCET,DVK 16 DEPT. OF ECE

Page 17: Naveen Doc

Moisturizing

Figure 5.1.1 Anti-aging and wrinkles

Figure 5.1.3 Iontophoresis

KMCET,DVK 17 DEPT. OF ECE

Page 18: Naveen Doc

Figure 5.1.4 estee lauder (for wrinkles)

5.2 USES OF PAPER BATTERY

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 (such as model aircraft), 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.

KMCET,DVK 18 DEPT. OF ECE

Page 19: Naveen Doc

5.3 DURABILITY

The use of carbon nano tubes 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’s essentially a regular piece of paper, but

it’s made in a very intelligent way,” said Linhardt, “We’re not putting pieces together — it’s a

single, integrated device,” he said.

CONCLUSION

In this paper we show the functionality of a non-encapsulated thin-film battery using

paper as electrolyte and also as physical support. Batteries able to supply a Voc≈.70V and

Jsc>100nA/cm2 at RH>60% were fabricated using respectively as anode and cathode thin metal

films of Al and Cu as thin as 100 nm. The battery is self rechargeable when exposed to relative

humidity above 40%, being Jsc highly influenced by RH>60%. In this case,Jsc varies from 150

nA/cm2 to 0.8 mA/cm2 , as RH varies from 60% to 85%. This constitutes the first step towards

future fully integrated self sustained flexible, cheap and disposable electronic devices, with great

emphasis on the so-called paper electronics.

KMCET,DVK 19 DEPT. OF ECE