Applications of Electroactive Polymers

Transcription

1 Applications of Electroactive Polymers

2 Applications of Electroactive Polymers Edited by Bruno Scrosati Chemistry Department University of Rome 'La Sapienza' Italy [cn[ SPRINGER-SCIENCE+BUSINESS MEDIA, B.V

3 First edition Springer Science+Business Media Dordrecht OriginalIy published by Chapman & HalI in 1993 Softcover reprint ofthe hardcover lst edition 1993 ISBN ISBN (ebook) DOI / Apart from any fair dealing for the purposes of research or private study, or criticism or review, as permitted under the UK Copyright Designs and Patents Act, 1988, this publication may not be reproduced, stored, or transmitted, in any form or by any means, without the prior permission in writing of the publishers, or in the case of reprographic reproduction only in accordance with the terms of the Iicences issued by the Copyright Licensing Agency in the UK, or in accordance with the terms of licences issued by the appropriate Reproduction Rights Organization outside the UK. Enquiries concerning reproduction outside the terms stated here should be sent to the publishers at the London address printed on this page. The publisher makes no representation, express or implied, with regard to the accuracy of the information contained in this book and cannot accept any legal responsibility or liability for any errors or omissions that may be made. A cataologue record for this book is available from the British Library Library of Congress Cataloging-in-Publication data available ~ Printed on permanent acid-free text paper, manufactured in accordance with the proposed ANSIjNISO Z X and ANSI Z

4 Contents List of contributors Preface Vll xi 1 Electrical and electrochemical properties of ion conducting polymers 1 Roger G. Linford 2 Electrical and electrochemical properties of electronically conducting polymers 29 William H. Smyrl and Mary Lien 3 Highly conductive polymer electrolytes 75 K.M. Abraham 4 Solvation mechanisms in low molecular weight polyethers 113 Michael Mendolia, H. Cai and Gregory C. Farrington 5 Lithium batteries with polymer electrodes Nobuhiro Furukawa and Koji Nishio 6 Lithium polymer batteries Bruno Serosati and Robin J. Neat 7 Electrochromic devices Marina M astragostino 8 Laminated electrochromic displays and windows Bruno Serosati

5 vi Contents 9 Functionalized conducting polymer membranes/films Takeo Shimidzu 10 Electroactive polymers in chemical sensors Mira J osowicz and J if{ J anata Index

6 Contributors K.M. Abraham EIC Laboratories Inc., 111 Downey Street, Norwood, Massachusetts 02062, H. Cai Department of Materials Science and Engineering, University of Pennsylvania, 3231 Walnut Street, Philadelphia, PA 19104, Gregory C. Farrington Department of Materials Science and Engineering, University of Pennsylvania, 3231 Walnut Street, Philadelphia, PA 19104, Nobuhiro Furukawa Sanyo Electric Co. Ltd, Functional Materials Research Center, Hashiridiani, Hirakata Osaka, Japan

7 viii Contributors Jiti Janata Molecular Science Research Center, Pacific Northwest Laboratory, Richland, WA 99352, Mira J osowicz Institut fur Physik, FakulHit fur Elektrotechnik, Universitat der Bundeswehr Munchen, Dw-8014 Neubiberg, Germany Mary Lien University of Minnesota, Corrosion Research Center, Department of Chemical Engineering and Materials Science, Minneapolis, MN Roger G. Linford Department of Chemistry, De Montfort University, The Gateway, Leicester, LEI9BH, UK Marina Mastragostino Dipartimento di Chimica, 'G. Ciamician', Universita di Bologna, Bologna, Italy Michael Mendolia Department of Materials Science and Engineering, University of Pennsylvania, 3231 Walnut Street, Philadelphia, PA 19104,

8 Contributors ix Robin J. Neat AEA Industrial Technology, Harwell Laboratory, Oxfordshire, OXll ORA, UK Koji Nishio Sanyo Electric Co. Ltd, Functional Materials Research Center, Hashiridiani, Hirakata Osaka, Japan Bruno Scrosati Dipartimento di Chimica, Universita di Roma, 'La Sapienza', 00185, Rome, Italy Takeo Shimidzu Division of Molecular Engineering, Graduate School of Engineering, Kyoto University, Kyoto 606, Japan William H. Smyrl University of Minnesota, Corrosion Research Center, Department of Chemical Engineering and Materials Science, Minneapolis, MN 55455,

9 Preface Electroactive polymers have been the object of increasing academic and industrial interest and in the past ten to fifteen years substantial progress has been achieved in the development and the characterization of this important new class of conducting materials. These materials are usually classified in two large groups, according to the mode of their electric transport. One group includes polymers having transport almost exclusively of the ionic type and they are often called 'polymer electrolytes' or, in a broader way, 'polymer ionics'. The other group includes polymeric materials where the transport mechanism is mainly electronic in nature and which are commonly termed 'conducting polymers'. Ionically conducting polymers or polymer ionics may be typically described as polar macromolecular solids in which one or more of a wide range of salts has been dissolved. The most classic example is the combination of poly(ethylene oxide), PEO, and lithium salts, LiX. These PEO-LiX polymer ionics were first described and proposed for applications just over ten years ago. The practical relevance of these new materials was immediately recognized and in the course of a few years the field expanded tremendously with the involvement of many academic and industrial laboratories. Following this diversified research activity, the ionic transport mechanism in polymer ionics was soon established and this has led to the development of new host polymers of various types, new salts and advanced polymer architectures which have enabled room temperature conductivity to be raised by several orders of magnitude. In addition, the various types of polymer ionics can be easily fabricated into flexible thin films with large surface areas where the ions are free to move and can conduct electricity as in conventional liquid electrolytes. This has opened the challenging possibility of replacing the difficult to handle, often hazardous, liquid solutions by chemically inert, thin-layer membranes for the fabrication of advanced electrochemical devices. Particularly relevant in this respect has been the technological goal of replacing liquid electrolytes in lithium, non-aqueous batteries by a thin film of a solid polymer electrolyte which would act both as electrode separator and as a medium for ionic

10 xu Preface transport. A number of commercial organizations in different countries are now actively developing these revolutionary electrochemical power sources. Finally, polymer ionics are of key importance for the fabrication and development of other exciting devices, such as laminated optical displays and sensors, and it is generally realized that in technological terms these ionically conducting polymers represent one of the most significant developments in solid state electrochemistry. The other group of materials, which covers the electronic conductors, includes conjugated polymers whose electronic structure may be significantly modified by electrochemical processes, sometimes designated as doping processes, which involve the oxidation (removal of 11: electrons) or the reduction (addition of 11: electrons) of the polymer chain. Typical examples are the heterocyclic polymers, such as polypyrrole, poly thiophene and their derivatives, and the polyanilines. The discovery of the electronically conducting polymers also dates a few years back when in the late seventies it was announced that the conductivity of polyacetylene, an intrinsically insulating polymer, could be raised by several orders of magnitude by redox processes run and controlled in electrochemical cells. Again the relevance of this discovery, which opened the route for previously inconceivable devices, was soon recognized. Indeed, conducting polymers, by deposition in thin-film configurations, may be used for the fabrication of novel types of electrodes to be employed in advanced, rechargeable lithium batteries and of novel types of organic conductors for the assembly of electronic components. Furthermore, by appropriate functionalization, selected conducting polymers may be exploited as specific electrodes in highly selective sensors. Finally, by taking advantage of the fact that upon doping the electronic band evolution is accompanied by changes in the optical properties, conducting polymers may find unique applications as optical switches in a series of devices of importance for energy control in the automobile and the building industries. In analogy to the case of their parent ionically conducting group, these electronic polymers have been the object of careful consideration during the last decade. Significant progress has been achieved in their characterization and today various industrial organizations are planning to launch new polymer-based devices of large commercial value. Typical examples are high volumetric energy density batteries for consumer electronics and rear view mirrors for worldwide production in major automobile industries. The purpose of this book is to review and discuss the impact that both groups of electroactive polymers may exert on the progress of modern electrochemical technology. Although the attention is mainly focused on applications, to facilitate full appreciation of the different topics treated in

11 Preface Xlll the book, some introductory chapters in which the basic properties of the cited polymers are discussed in a straightforward, yet rigorous way, are also included. This book, by providing the rare opportunity of presenting the views of leading experts in the field, will be a valuable reference for scientists, engineers, students, and, generally, readers who are interested in the investigation and the exploitation of this fascinating new class of conducting materials. Bruno Scrosati