20-12-2012, 05:59 PM
Batteries power a wide range
Batteries power.docx (Size: 1.38 MB / Downloads: 92)
ABSTRACT
Batteries power a wide range of electronic devices including phones, laptop computers and medical devices such as cardiac pacemakers and
defibrillators. In the near future, batteries may also help fight global warming by improving the performance of electric or hybrid vehicles with zero or reduced carbon emissions. With the ever increasing demand for efficiency and design, there is a need for ultrathin, safe and flexible energy storage options. Power sources are needed for the operation of the paper electronics, and ideally, a power source directly integrated onto paper would be preferred for easy system integrations
There is a strong interest in thin, flexible energy storage devices to meet modern society needs for applications such as interactive packaging, radio frequency sensing, and consumer products. In this article, we report a new structure of thin, flexible Li-ion batteries using paper as separators and free-standing carbon nanotube thin films as both current collectors. The current collectors and Li-ion battery materials are integrated onto a single sheet of paper through a lamination process. The paper functions as both a mechanical substrate and separator membrane with lower impedance than commercial separators. The CNT film functions as a current collector for both the anode and the cathode with a low sheet resistance (_5 Ohm/sq), lightweight (_0.2 mg/ cm2), and excellent flexibility. After packaging, the rechargeable Li-ion paper battery, despite being thin (_300 _m), exhibits robust mechanical flexibility and a high energy density (108 mWh/g). These devices can be paper thin, flexible, lightweight and manufactured by a low cost, roll-to-roll printing process.
.
paper batteries are 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 supercapacitor .This combination allows the battery to provide both long-term, steady power production and bursts of energy. These thin batteries can be folded, cut or otherwise shaped for different applications without any loss of efficiency. Cutting one in half , halves its energy production. These Can be stacked in multiples of power output.
INTRODUCTION
Need
The basic problems associated with the present Electro-Chemical batteries are: (1) Limited Life- Time: Primary batteries irreversibly (within limits of practicality) transform chemical energy to electrical energy. 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. But, Rechargeable batteries are still costlier than Primary Batteries in the markets of developing countries like India. (2) Leakage: If leakage occurs, either spontaneously or through accident, the chemicals released may be dangerous. For example, disposable batteries often use zinc "can" as both a reactant and as the container to hold
the other reagents. If this kind of battery is run all the way down, or if it is recharged after running down too far, the reagents can emerge through the cardboard and plastic that forms the remainder of the container. The active chemical leakage can then damage the equipment that the batteries were inserted into. (3)Environmental Concerns: The widespread
use of batteries has created many environmental concerns, such as toxic metal pollution. Metals such as Cadmium, Mercury, Lead, Lithium and Zinc have been identified as highly toxic metals. Also, batteries may be harmful or fatal if swallowed. 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.
Integration of electronics onto existing, widely used paper could bring unprecedented opportunities for consumer electronics[1].
There has to be a compromise between the charge producing device (Battery) and a charge storing device(Capacitor). Batteries (whether primary or secondary) cannot possess indefinite recyclability. Same is the case with capacitors. So, if a balance be sought between them in such a way so as to utilize the properties of both, the results would be more rewarding. Owing to this fact and to the miraculous properties of the Carbon nanotubes, there has been a steady and progressive interest in the global scientific community aimed at its utilization in the production of Paper Batteries. This paper reports on the use of cellulose paper simultaneously as electrolyte, separation of electrodes, and physical support of a rechargeable battery. The deposition on both faces of a paper sheet of metal or metal oxides thin layers with different electrochemical potentials, respectively as anode and cathode, such as Cu and Al, lead to an output voltage of 0.70 V and a current density
that varies between 150 nA/cm