Conducting polymer batteries

Figure 5.21 Theoretical energy density of a Li/conductive polymer battery. (Assumed cell voltage 3.0 V.)...

To compete with the currently available batteries, however, the conducting polymer batteries must meet the following requirements [72] ... 

A conducting polymer battery system having a configuration of a dry cell [Leclanche] type, which can be recharged with a cyclability of 100 cycles would be a preferred choice. A primary cell—Leclanche cell (dry cell) is represented as follows ... 

The last section briefly examines the applications potential of highly conducting organic polymers. Some of the applications, such as conducting polymer batteries, might be near at hand. Other applications depend upon obtaining the materials improvements contemplated in the third section. 

In this context the performance of electronically conducting polymer batteries was very briefly commented by A. MacDiarmid and R. Baughman. The state of the art of the Allied project was stated as a 55 Wh/Kg energy capacity at a typical discharge rate of C/10, no significant capacity decline over 250 cycles and a self-discharge less severe than Nickel/Cadmium battery. Discussion on electronically conductive polymer batteries was cut short, by the Discussion Leader as the Allied Chemical scientist declined to elaborate on any further results for confidentialty reasons. 

Table 3. Battery Characteristics for Conductive Polymer Electrodes...

The first tme commercialization of a conductive polymer electrode in a battery ceU has been carried out by Bridgestone/Sienko who market a... 

An example of an ionically conductive polymer is polyethylene oxide containing LiC104, which is used as a solid phase electrolyte in batteries. 

A completely separate family of conducting polymers is based on ionic conduction polymers of this kind (Section 11.3.1.2) are used to make solid electrolyte membranes for advanced batteries and some kinds of fuel cell. 

The presence of polymer, solvent, and ionic components in conducting polymers reminds one of the composition of the materials chosen by nature to produce muscles, neurons, and skin in living creatures. We will describe here some devices ready for commercial applications, such as artificial muscles, smart windows, or smart membranes other industrial products such as polymeric batteries or smart mirrors and processes and devices under development, such as biocompatible nervous system interfaces, smart membranes, and electron-ion transducers, all of them based on the electrochemical behavior of electrodes that are three dimensional at the molecular level. During the discussion we will emphasize the analogies between these electrochemical systems and analogous biological systems. Our aim is to introduce an electrochemistry for conducting polymers, and by extension, for any electrodic process where the structure of the electrode is taken into account. 

This distribution causes a problem the best-described conducting polymers interchange anions with the electrolyte, and the Li electrode liberates Li+during discharge. The salt accumulates in the electrolyte [Fig. 32(a)], requiring a great volume and mass in order to avoid the precipitation of the salt. This fact reduces the specific energy of the battery to impractical values. 

Figure 32. Different electrodic assemblies to construct batteries using conducting polymers.

Conducting polymers have found applications in a wide variety of areas,44 45 and many more have been proposed. From an electrochemical perspective, the most important applications46 appear to be in batteries and supercapacitors 47,48 electroanalysis and sensors49-51 electrocatalysis,12,1, 52 display and electrochromic devices,46 and electromechanical actuators.53... 

The knowledge that conducting polymers can be charged, i.e. oxidized and reduced, raised early on the question of possible applications, such as the construction of a polymer battery. But basic research was long unable to explain the charge storage mechanism. 

The enormous efforts put into the basic research and development of conducting polymers are naturally related to hopes of feasible technical apphcations The starting point of this development was the discovery that PA can fimction as an active electrode in a rechargeable polymer battery. Since then, the prospects of technical application have grown considerably Apart from the battery electrode, conducting polymers are discussed as potential electrochromic displays... 

There are difficulties in analysing conductive polymers, and information on the relationship between structure and properties somewhat difficult to obtain. These materials have already found a variety of uses, including flat panel displays, antistatic packaging and rechargeable batteries, and other applications are likely to emerge in the future. 

XI. LIGHT-EMITTING DIODES AND BATTERIES BASED ON CONDUCTING POLYMERS... 

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