Any achievement, be it scholastic or otherwise does not depend solely on the individual efforts but on the guidance, encouragement and cooperation of intellectuals, elders and friends. A number of personalities, in their own capacities have helped me in carrying out this seminar work. I would like to take this opportunity to thank them all.
First of all, I would like to express my hearty gratitude to Dr.V.Sridhar, Principal, and P.E.S.C.E for giving me this opportunity to enrich our knowledge.
I would like to express my hearty gratitude to Dr.K.N.Muralidhara, Head of the Department of Electronics and Communication, P.E.S.C.E for providing permission and facilities to conduct the seminar in a systematic way
I would like to express my hearty gratitude to S.Jyothi Asst.Professor, seminar coordinator, Department of Electronics and Communications, P.E.S.C.E for her guidance, regular source of encouragement and assistance throughout this seminar.
I express my sincere gratitude to S.Jyothi Asst.Professor, seminar guide, Department of Electronics and Communications, P.E.S.C.E for inspiring and sincere guidance throughout the seminar.
I am thankful to all the faculty members in the Department of Electronics and Communications, P.E.S.C.E for their constant support.
I would like to thank my parents and friends for their moral support. Thanks for being always there. Finally, I thank God, for his blessings.
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.
Table of Contents
Introduction to batteries……….5
Principle of operation of cell……….………7
Types of battery………...81.4
Life of battery………...91.6
Fabrication of paper battery……….………….…...13
Working of paper battery……….………..…...14
Advantages of paper battery………...……..15
Limitations of paper battery………..………....16
Applications of paper battery………...………….16
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
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
Accumulator- A rechargeable battery or cell
Ampere-Hour Capacity- The number of ampere-hours which can be
delivered by a battery on a single discharge.
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.
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, hours, or similar units. The capacity in watt-hours is equal to the capacity in ampere-watt-hours multiplied by the battery voltage.
Cutoff Voltagefinal - 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.
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 the same battery would be 320 mA and C/10 would be 160 mA.
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-amp-hours) or as watt-amp-hours.
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.
Cycle- One sequence of charge and discharge.
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.
Electrochemical Couple -The system of active materials within a cell
that provides electrical energy storage through an electrochemical reaction.
Electrode -An electrical conductor through which an electric current
enters or leaves a conducting medium
-A chemical compound which, when fused or dissolved in
certain solvents, usually water, will conduct an electric current.
Internal Resistance -The resistance to the flow of an electric current
within the cell or battery.
Open-Circuit Voltage- The difference in potential between the
terminals of a cell when the circuit is open (i.e., a no-load condition).
Voltage, cutoff- Voltage at the end of useful discharge. (See Voltage,
Voltage, end-point- Cell voltage below which the connected equipment
1.2 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.
1.3 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
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
1.4 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.
Fig. 1.4 USB cell
1.5 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.  This is known as the "self-discharge" rate and is
due to non-current-producing
occur within the cell even if no load is applied to it
.The rate of the side
reactionsis 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.
1.6 Hazards related to batteries
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.
Many battery chemicals are corrosive, poisonous, or both. If leakage occurs, either spontaneously or through accident, the chemicals released may be dangerous
The widespread use of batteries has created many environmental concerns, such as toxic metal pollution. Battery manufacture consumes resources and often involves hazardous chemicals. 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.
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
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 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, mostlyelectric vehicles. Further, the medical uses are particularly attractive because they do not contain any toxic materials.
Fig.2 paper battery
3. 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 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.)
4. FABRICATION OF PAPER
The materials required for the preparation of paper battery are
a. Copier paper b. Carbon nano ink c. Oven
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.
5. 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
The devices are formed by combining cellulose with an infusion of aligned 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.
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, "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.
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.
• Presently, the devices are only a few inches across and they have to be scaled up 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.
Pace makers in heart (uses blood as electrolyte)
Used as alternate to conventional batteries in gadgets
Powered smart cards RF id tags
Smart toys, children sound books
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.
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.