GB2184738A - Electronically conducting polypyrrole and copolymers of pyrrole, compositions containing them, methods for making them, and electrochemical cells using them - Google Patents

Abstract

An electronically conducting composition comprises electropolymerized polypyrrole or a copolymer of pyrrole and contains one or more low mobility anions having an average ionic transference number for said anions during reduction of less than 0.1. The composition may be either porous or non-porous material in the form of films, powders, dendriform materials, or various shapes formed as desired by pressing powders of the composition. The electronically conducting composition can be prepared by several processes which are described, and a preferred process involves a multi-phase system, and more preferably, a two-phase system, one phase being aqueous. These compositions are stable over a range of chemical and electrochemical conditions and are useful in a number of applications, including electrodes for electrochemical cells such as electrochemical energy storage cells.

Description

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GB 2 184 738 A

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SPECIFICATION

Electronically conducting polypyrrole and co-polymers of pyrrole, compositions containing them, methods for making them, and electrochemical cells using them

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Technical Field

This invention relates to polypyrrole and co-polymers of pyrrole. More particularly, this invention relates to electronically conducting compositions comprising electropolymerized polypyrrole ora co-polymer of pyrrole; to methods for making electronically conducting polypyrrole or co-polymers of pyrrole; and to 10 electrochemical cells comprising polymeric electrode means, said polymeric electrode means being positive and/or negative and comprising electronically conductive polypyrrole or a co-polymer of pyrrole.

Background of the Invention

The term polypyrrole means polymers containing polymerized pyrrole rings. A pyrrole ring is an unsatura-15 ted five membered ring containing four carbon atoms and one nitrogen atom. Polypyrrole is not limited herein to polymers of unsubstituted pyrrole monomer, nor is it limited to polymerization at specific sites in the pyrrole rings. A preferred polypyrrole for use in accordance with the present invention is the 2,5 polymerized homopolymer of unsubstituted pyrrole. The term co-polymer of pyrrole means any polymer containing pyrrole and/or substituted pyrrole monomers and/or one or more other monomers copolymerizable 20 therewith.

Polypyrrole belongs to the general class of electronically conducting organic polymers, and more specifically is one of the group of polymers which may, under certain conditions, have conductivities exceeding about 1 ohm~1cm"1 that have been developed in recentyears. Other well-known members of this group are polyacetylene, poly-p-phenylene, poly-p-phenylene sulfide and poly (2,5 thienylene).

25 Pyrrole black, a polymeric powdered material formed by oxidizing pyrrole in homogeneous solution (e.g. with H202) has been known for many years. Gardini, Adv. HeterocycL Chem, 75,67 (1973). An electrochemical method of producing polypyrrole as a powderfilm on an electrode has been reported. A. Dall' Olio et al., Comp. Rend., 433,267c (1968). Electropolymerization to produce polymerfilmsfrom pyrrole has been reported. Diaz etal,J. Chem. Soc, Chem, Comm.,635, (1979) (hereinafter Diaz etal, J. Chem. Soc, Chem. Comm., 30 397, (1980) (hereinafter Diaz (II)); Diaz, Chemica Scripta, 17,45, (1981) (hereinafter Diaz (III)); and Kanazawa et al.,,/. Chem. Soc., Chem. Comm., 954(1979) (hereinafter Kanazawa (I)). Electropolymerized polypyrrole from substituted pyrroles has been reported. Diaz (II); Diaz etal., J. Electroanal Chem., 129,115, (1981) (hereinafter Diaz (IV)); Diaz etal., J. Electroanal Chem., 130,181, (1981) (hereinafter Diaz (V)). Co-polymer films produced by electropoiymerizing mixtures of pyrrole and substituted pyrrole have also been reported. A mixture of 35 pyrrole and N-methyl pyrrole has been polymerized and it is believed that both monomers are incorporated into the polymer. Diaz (II); Diaz, Proc. Int. Conf. on Low Dimensional Synthetic Metals Chemica Scripta, 17, 0000, (1981) (hereinafter Diaz (VI)); and Kanazawa etal.,/ Synth Metals,4,119, (1981) (hereinafter Kanazawa

(ID).

Polypyrrole is electronically conducting in the charged or oxidized state (black), and is produced in this 40 state by electropolymerization. When it is completely reduced to the neutral or discharged state (yellow), it is an electronic insulator. The electropolymerized polypyrrole is produced in the oxidized, i.e. conductive, state and (unlike other conducting polymers such as polyacetylene) does not require any subsequent chemical or electrochemical treatment to increase its conductivity above 1 ohm^crrf1-Acounter-anion is incorporated into the material during the electropolymerization process to balance the positive charge on the polymer 45 backbone. Diaz (III).

Polypyrrole can be made as powders. Gardini, supra. Polypyrrole can also be electropolymerized as a continuous film on electrodes. The highest electronic conductivities reported for the continuous films are of the order of about 100 ohm"1cm_l. Diaz (I); Kanazawa eta I. ,Syn. Metals, 1,329, (1980) (hereinafter Kanazawa (III)). These conductivities can be orders of magnitude lower depending on the counter-anion incorporated. 50 A large number of counter-anions have been used, including BF4", PF6", AsF6", CIO4", HS04", CF3SO3", CH3C6H4S03~, CF3COO", HC2O4", Fe(CN)63". Diaz(IV); Diaz(VI); Kanazawa (I); and Noufi etal, J. Electrochem. Soc., 725,2596,(1981).

N-substituted pyrroles have been polymerized, including methyl, ethyl, n-propyl, n-butyl, isobutyl and phenyl and substituted phenyl pyrroles. Diaz (IV); Diaz etal.. Electrochemical Society Extended Abstracts, 55 Vol. 82-1. Abstract No. 617, (1982) (hereinafter Diaz (VII)). These materials have reported electronic conductivities orders of magnitude lowerthan polypyrrole itself. Kanazawa (II); Diaz (VII). It has been reported that beta-substituted pyrroles such as 3,4 dimethyl pyrrole have been polymerized. Gardini, supra.

The polymers have been prepared to date with non-aqueous solvents, typically acetonitrile, (Diaz (I); Diaz (II); and Diaz (VI)), containing a dissolved salt which provides the counter-anion. It is known that the physical 60 properties of the resulting films are sensitive to the formation conditions. For example, in acetonitrile, small traces of water in the solvent produce a film with a smoother surface than that produced in anhydrous acetonitrile. Diaz (VI). The polypyrrole tetrafluorobo rate films produced by Diaz etal. are continuous, spacefilling and very poorly crystalline with a density of 1.48 g cm"3. Kanazawa (III).

Polypyrrole films are thermally stable at room temperature and are insoluble in common solvents. Diaz (I); 65 Kanazawa (II); and Tourillon et al., Electrochemical Society Extended Abstracts, Vol. 82-1, Abstract No. 618,

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(1982). Polypyrrole in the oxidized form is reported to be chemically stable in ambient conditions of 02 and moisture for several months. Diaz etal .,J. Electroanal. Chem., 121,355, (1981)) (hereinafter Diaz (VIII)); Watanabe et al. Bull. Chem. Soc. Jpn., 54,2278, (1981). Polypyrrolefluoroborate films have been shown to be unstable underoxidative conditions such as potentials greaterthan + 0.6 V. (SCE) or in the presence of 5 halogens. Bull et al, J. Electrochem. Soc., 129,1009. (1982).

Polypyrrole can be driven repeatedly between the conducting and non-conducting state. Bull etal, supra; Diaz etal, "Conducting Polymers", Polymer Sci. & Technology, p. 149 et. seq., Plenum Press, N.Y.,(1981) (hereinafter Diaz (IX)). Rapid complete switching is reported to require the use of thin films (i.e., less than aboutO.1 micrometer) and switching is difficultforthicknesses greaterthan about 1 micrometer. Diaz(ll); 10 Diaz (IX). It has been shown that although a film may contain BF4"counter-anions when it isformed (i.e., isthe charged state) BF4" is no longer present in thefilm when it is in the neutral (i.e., reduced or discharged) state. Diaz (IV). It has been suggested that both the anion and the cation of the electrolyte salt affect ion diffusion during reduction and oxidation of polypyrrolefilms. Diaz (IV).

Polymers have been produced with different degrees of oxidation, depending on the anion and/orsubsti-15 tuents. Most of these material have degrees of oxidation around 0.25 (i.e., one quarter of the polymer rings are

Summary of the Invention

The compositions of the present invention are electronically conducting compositions which comprise an 20 electropolymerized polypyrrole or co-polymer of pyrrole, and these compositions may be either porous or non-porous materials in theform of films, powders, dendriform materials, or various shapes formed as desired by pressing powders of the compositions of the invention. These compositions are particularly suitable in the formation of positive and/or negative polymeric electrodes for use in electrochemical cells such as, for example, electrochemical energy storage cells.

25 The present invention contemplates the provision of a porous electronically conducting composition comprising an electropolymerized polypyrrole or co-polymer of pyrrole, said composition characterized by an apparent density of from about0.01 g cm"3 up to the bulk density of said polypyrrole or co-polymer and a surface area of at least two times the surface area of a smooth film of bulk density of the composition. The invention further provides for an electrochemical cell comprising polymeric electrode means, said polymeric 30 electrode means being positive and/or negative and comprising theforegoing composition.

Further, the present invention provides foran electronically conducting composition comprising electropolymerized polypyrrole or a co-polymer of pyrrole, said composition containing one or more low mobility anions characterized by an average ionictransference numberfor said low mobility anions during reduction of less than about 0.1. The invention further provides for an electrochemical cell comprising polymeric elec-35 trade means, said polymeric electrode means being positive and/or negative and comprising theforegoing composition.

Further, the present invention contemplates the provision of a method of preparing electronically conducting polypyrrole or co-polymers of a pyrrole which comprises electropolymerization of pyrrole or a copoly-merizable mixture containing pyrrole at an electronically conductive surface in an electrolytic bath, the 40 method comprising the steps: (A) immersing an electronically conductive surface in an electrolytic bath comprising at least one liquid and at least one non-miscible liquid or gas or finely divided solid particles wherein the pyrrole orthe copolymerizable mixture containing a pyrrole is one of the liquids or is dissolved in at least one of the liquids, and (B) passing an electric current through said bath at a voltage sufficientto electropolymerize the pyrrole or copolymerizable mixture containing a pyrrole at the electronically conduct-45 ive surface. In a preferred embodiment of this method the electrolytic bath comprises an aqueous mixture comprising pyrrole, or mixture of pyrrole and a copolymerizable monomer and water. The invention further providesforan electrochemical cell comprising polymeric electrode eans, said polymeric electrode means being positive and/or negative and comprising electronically conducting polypyrrole or a co-polymer of pyrrole prepared in accordance with the foregoing method.

50 Further, the present invention provides for a method for preparing electronically conducting polypyrrole or a co-polymer of pyrrole which comprises the steps of: (A) electropolymerizing a pyrrole or a copolymerizable mixture of a pyrrole atan electronically conductive surface in an electrolytic bath by (1) imersing an electronically conductive surface in an electrolytic bath which comprises (a) an aqueous dispersion of a pyrrole, ora mixture of said aqueous dispersion and at least one copolymerizable monomer or (b) a pyrrole ora mixture 55 of a pyrrole and/or at least one copolymerizable monomer, water and a water-immiscible diluent, (2) agitating the bath, and (3) passing an electric current through said bath at a voltage sufficient to electropolymerize the pyrrole or pyrrole mixture and deposit the polymer or co-polymer on the electronically conductive surface, and (B) removing said polymer or co-polymerfrom the conductive surface. In a preferred embodiment of this method, the electrolytic bath comprises an aqueous mixture comprising pyrrole or a copolymerizable 60 mixture of pyrrole, water, and one or more low mobility anions which are incorporated into the polypyrrole by electropolymerization and which anions are characterized by an average ionictransference numberfor said low mobility anions on reduction of less than about 0.1. The invention further provides for an electrochemical cell comprising polymeric electrode means, said polymeric electrode means being positive and/or negagive and comprising polypyrrole or a co-polymer of pyrrole prepared in accordance with theforegoing 65 method.

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Further, the present invention provides for a method of preparing electronically conducting polypyrrole or a co-polymer of pyrrole which comprises electropolymerization of a pyrrole ora copolymerizable mixture containing a pyrrole at an electronically conductive surface in an electrolytic bath by (A) immersing an electronically conductive surface in an electrolytic bath comprising (i) a pyrrole or a mixture of a pyrrole with a 5 copolymerizable monomer, (ii) one or more low mobility anions which are incorporated into the polypyrrole or co-polymer of pyrrole and which are characterized by an average ionic transference numberfor said low mobility anions during reduction of the polypyrrole or co-polymer of less than about 0.1, and (iii) anorganic diluent, and (B) passing an electric currentthrough said bath at a voltage sufficientto electropolymerize the » pyrrole or copolymerizable mixture containing pyrrole at the electronically conductive surface. The invention

10 further provides for an electrochemical cell comprising polymeric electrode means, said polymeric electrode means being positive and/or negative and comprising polypyrrole or a co-polymer of pyrrole prepared in » accordance with theforegoing method.

Brief Description of the Drawings 15 Figure 1 is a sectional side elevational view of a laboratory scale lithium cell illustrating the present invention in a particularform;

F/firure2 is a side elevational view of a laboratory scale electrochemical cell illustrating an alternate embodiment of the present invention in a particularform;

Figure 3 is a perspective view of an electrochemical energy storage cell illustrating another alternate em-20 bodimentofthe present invention in a particularform;

Figure 4\s a sectional side elevational view of the electrochemical cell illustrated in Figure 3;

Figure 5\s a sectional side elevational view of an electrochemical energy storage cell illustrating another alternate embodiment of the present invention in a particularform;

Figure 6 is a sectional side elevational view of a layered or stacked electrochemical energy storage cell 25 illustrating another alternate embodiment ofthe present invention in a particularform; and

Figure 7\s a sectional side elevational view of a layered or stacked electrochemical energy storage cell illustrating still another alternate embodiment of the present invention in a particularform.

Description of the preferred Embodiments 30 In a preferred embodiment of this invention, the electronically conducting compositions of the invention contain at least one low mobility anion, A, which has a strong tendency to be retained in the composition on reduction. The transport of ionic charge to compensate the change in oxidation state ofthe polymer is then carried out principally by ions ofthe electrolyte in which the redox process is carried out. The low mobility anions may be characterized by their ionictransference numbers. The ionictransference number is defined 35 as the fraction of the ionic current carried by the particular anion averaged over substantially full reduction of the composition. The polymer is formed in the oxidized state (black) which is electronically conductive and can be reduced to the neutral state (yellow) which is insulating. However, for practical purposes, the reduction of thick (500 millimicron or greater) films does not proceed to completion even at very negative potentials. The material remains black in appearance and retains some electronic conductivity although above 40 about 90% reduction its resistance may increase. In general, the low mobility anions utilized in the compositions of this invention will be characterized by an average ionictransference numberfor said low mobility anions during reduction of less than 0.1 and preferably less than about 0.05. A most preferred low mobility anion is one characterized by an average ionictransference numberfor said low mobility anions during reduction of less than 0.01.

45 These transference numbers may be determined by elemental analysis ofthe polymers before and after reduction. Thus, the transference number (tA) ofthe low mobility anion may be defined asfollows:

" tA = ANA/(NA)o

50 wherein (NA)0 is the number of moles ofthe charge compensating anion initially in the polymer (when it is in '» the oxidized state) and ANa is the change in the number of moles ofthe anion aftersubstantially full reduction

(towards the neutral state).

The porous compositions ofthe invention also are characterized by an apparent density of from about 0.01 g cm"3 up to about the bulk density ofthe polypyrrole or co-polymer of pyrrole.

55 Bulk ortheoretical density of the polymers is the density of continuous, pure polymer containing no voids, pores, cavities or inclusions. The bulk or theoretical density can usually be determined by flotation methods. Apparent density for less dense forms of the polymer such as the porous materials is defined from the mass of the polymer and the volume calculated from the external dimensions ofthe material. Since voids, cavities, etc., are included in the porous-type materials, their apparent density will be lowerthan the bulkdensity. 60 The porous composition ofthe invention also is characterized as having an electrochemically accessible surface area of at least two times the surface area of a smooth film of bulk density ofthe polymer orco-polymer. Preferred materials have significantly greater surface areas, (e.g., 1000 times or more than that of a smooth film of bulkdensity).

The electronically conducting compositions ofthe present invention comprise either polypyrrole(s) or 65 co-polymer(s) of pyrrole which may be obtained by (a) polymerizing mixtures of a pyrrole with other co-

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polymerizable monomers or by (b) grafting a co-monomer(s) to a polypyrrole polymer or by (c) grafting a pyrrole monomer(s) to a preformed polymer based on a monomer otherthan pyrrole.

The pyrrole monomers which can be electropolymerized may be pyrrole or substituted pyrroles such as the N-sustituted or C-substituted pyrroles as described more fully below. Homopolymers of these pyrroles, 5 and preferably the homopolymers of unsubstituted pyrrole are included. 5

Co-polymers of a pyrrolecan be prepared, for example, by polymerizing a mixture of pyrrole and one or more substituted pyrroles which may be substituted either on the nitrogen atom or at one or more ofthe ring carbon atoms in the beta position. Preferably,thesubstituentisa lower alkyl group containing from 1 to7 carbon atoms, and it is more preferably a methyl group. Thus, for example, co-polymers of pyrrole and 10 N-methylpyrrole or 3,4-dimethyl pyrrole can be prepared in accordance with the methods ofthe invention. 10 Alternatively, pyrrole can be co-polymerized with other heterocyclic ring compounds including those containing nitrogen (e.g., pyridine, aniline, indole, etc.), furan andthiopheneorwith other aromatic orsubstitu-ted aromatic compounds.

The low mobility anions which are incorporated into the compositions ofthe invention may be either 15 organic or inorganic anions. Examples ofthe low mobility inorganic anions useful in the present invention 15 includetransition metal complexes such asferricyanide, nitroprusside, iron/sulfur cluster compounds such as the redox centers ofthe rubredoxins and the ferredoxins, boron cluster compounds, cobalt hexacyanide, othertransition metal cyanide complexes, nitroprussidecomplexes, and other transition metal oxy complexes or sulfides or chalcogenide complexes, e.g. W04", M0O4", Mo(CN)s4", Fe4S4C4Hi2", Cr04",etc.

20 Preferably, the low mobility anions included in the compositions ofthe present invention are organic 20

anions. Examples of organic anions include those derived from organic sulfates or sulfonates, and these may be alkyl, cycloalkyl,aryl, arylalkyl or alkarylsulfatesand sulfonates. The anions which are useful in the present invention may contain more than one anionic site, i.e., more than one ionizable group per molecule, e.g. more than one sulfonic acid group per molecule. The sulfonates and sulfates useful as the low mobility 25 anionsinthecompositionsofthepresentinventionmayberepresentedbythefollowingformulas: 25

R1(S03)X Formula I

30 R2(S03)X Formula II 30

X

R1(0S03)* Formula III

35 v_ 35

R2(0S03r Formula IV

40 R2yT(S03)X Formula V 40

X

R1yT(S03)X Formula VI

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In the above formulas, R1 is an aliphatic or an aliphatic substituted cycioaliphatic hydrocarbon or an essentially hydrocarbon group generally free from unsatu ration and usually containing up to about 30 carbon atoms although it may be polymeric and contain more than 30 carbon atoms. When R1 is aliphatic, it usually contains at least about 4 carbon atoms, and when R1 is alkyl substituted cycioaliphatic, the alkyl substituents 50 preferentially contain from 1 to 4 carbon atoms. Specific examples of R1 include butyl, hexyl, octyl lauryl, 50

cetyl, octadecyl and groups derived from petroleum, saturated and unsaturated paraffin wax, and olefin polymers including polymerized mono-olefins and diolefins containing from 2 to about 8 carbon atoms per olefinic monomer unit. R1 can also contain other substituents such as phenyl, cycloalkyl, hydroxy, mercapto,

halo, nitro, amino, lower alkoxy, lower alkyl mercapto, carbalkoxy, oxo and thio, or interrupting groups such 55 as -N H-, -0-, -S-, but prefera bly its overa 11 hydrocarbon character is retained. 55

R2 generally is a hydrocarbon or essentially hydrocarbon group containing from 1 to about 30 carbon atoms, although it may be polymeric and contain more than 30 carbon atoms. R2 is preferably an aliphatic hydrocarbon group such as alkyl aklenyl, or alkylaryl. R2 also may contain substituents such as those enumerated above, including the above indicated interrupting groups, provided the essentially hydrocarbon char-60 acterthereof is retained. 60

The group T in the above formulas V and VI is a cyclic nucleus which may be derived from an aromatic hydrocarbon such as benzene or from a heterocyclic compound such as pyridine. Ordinarily, T is an aromatic hydrocarbon nucleus and especially benzene. The subscript and super-script x represents the average number of ionized groups per molecule. The anion may contain additional sulfate or sulfonate groups which 65 are not ionized but associated with some cationic species. In formulas I through VI, x may have a value of up 65

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to 1000 or more when R1 or R2 is polymeric, but is preferably from 1 to 10, more preferably from 1 to 6, and generally is 1. The subscript y in Formulas V and VI is a number ranging from 1 to 5 and preferably is 1.

Anioniccompounds containing the anions represented above by Formulas I through VI are available commercially or can be prepared readily by techniques known in the art. Examples are salts with alkali or alkaline 5 earth metals, or ammonium salts. 5

Examples of sulfonates useful in the invention include the anions ofthe following acids; hexyl sulfonic acid, octyl sulfonic acid, dodecyl sulfonic acid, octyldecyl sulfonic acid, lauryl sulfonic acid, mahogany sulfonic acid, paraffin wax sulfonic acid, benzene sulfonic acid, napthalene sulfonic acid, laurylcyclohexyl sulfonic acid, dodecyl benzene sulfonic acid; polyethylene sulfonic acids of various molecular weights; poly-10 styrene sulfonic acids of various molecular weights, etc. Styrene maleic anhydride co-polymers bearing 10

groups on the rings or styrenemaleic anhydride co-polymers which have been partially orfully converted to the corresponding imide sulfonates are also useful anionic species in the invention; such materials are derived from styrene maleic anhydride co-polymers typically having inherent viscosity of about 0.06 to about 1, preferably about 0.06 to about 0.3 dl g"1 measured at30°Cin acetone, 0.4-1 gdl"1.

15 A preferred embodiment includes anions derived from aliphatic compounds containing two sulfonic acid 15 groups and may be represented by theformula

(CH2)n(S032 Formula VII

20 20

wherein n is an integer from about 2 to 20 or more and preferably about 2 to 12. These disulfonic acid salts can be prepared by techniques known in the art such as by the reaction of alkylene dihalides with sodium sulfite. Specific examples of such compounds include the salts of ethane disulfonic acid, 1,4-butane disulfonic acid, 1,5-pentane disulfonic acid, 1,6 hexane disulfonic acid, 1,8-octane disulfonic acid and 1,10-25 decane disulfonic acid. 25

Examples of sulfates which are useful include alkyl sulfates such as lauryl sulfate; and polyethylene sulfates of various molecular weights.

Another class of sulfates which are useful as the low mobility anions in the compositions ofthe present invention are polysulfated polyhydroxy compounds. Such compounds can be obtained by reacting poly-30 hydroxy compounds with an appropriate reagent such as chlorosulfonic acid thereby converting one or 30

more ofthe hydroxy groups to sulfate groups. Examples of polyhydroxy compounds which can be used to prepare such polysulfates include pentaerythritol, mannitol,trimethylolpropane, dipentaerythritol, etc. As mentioned, one or more ofthe hydroxy groups in these polyhydroxy compounds can be sulfated to produce a variety of products. Ammonium sulfates can be prepared directly from polyhydroxy compounds by reac-35 tionwithan aminosulfonic acid in the presence of a diluent such as dimethyl formamide. 35

Amido, and preferably acrylamido alkane sulfonic acid anions can be used in the compositions ofthe invention. Specific examples of such anions include: 2,2-bisacrylamido-1,1-dimethylethanesulfonicacid anion; 2-acrylamido-2-methyI propane sulfonic acid anion; and poly (2-acrylamido-2-methyl propane sulfonic acid sodium salt of various molecular weights.

40 The low mobility anions included in the compositions ofthe present invention may also be derived from 40 pentavalent phosphorous compounds. Examples of such phosphorous compounds are phosphates, phosphonatesand phosphinates.The phosphorous compounds useful as the low mobility anions in the compositions ofthe present invention may be represented by the following formulas:

R3(X1)

/ R4(X2)b

X4

II

P—

Formula VIII

X4

II

R3(X1)a P X3

I

X2

Formula IX

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X4

li

R4(X1)a-P -X3

I

X2

2-

FormuiaX

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R3— (X1 )a

X4

li

P-X3

I

(X2)b

I

R4

z-

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Formula XI

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-(X1)

(X^a

X4

II

P-X3

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(X2)b R3

X4

II

P-X3

I

X2

z-

2z-

X4

II

(X^a — P-X3 X2

2z-

FormulaXII

Formula XIII

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Formula XIV

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50 In the above formulas R3 is R1 orR1yT as defined above, or can be hydrogen, an alkali metal (e.g., lithium, 50 sodium, potassium, etc.) or an alkaline-earth metal (e.g., calcium, magnesium, etc.). R4 is R2 or R2yT, as defined above, or can be hydrogen, an alkali metal (e.g., lithium, sodium, potassium, etc.) or an alkaline earth metal (e.g., calcium, magnesium, etc.). Each of X1, X2, X3 and X4 is oxygen or sulfur; and each a and b is 0 or 1. The subscript and superscript z represents the average number of ionized groups per molecule. In Formulas 55 XI through XIV, z may be a value of up to 1000 or more when R1 or R2 is polymeric, but is preferably from 1 to 55 10, more preferably from 1 to 4, and generally is 1. Thus, it will be appreciated that the pentavalent phosphorous compounds may be for example, organophosphoric,phosphonic or phosphinic compounds including the acids, alkali metal salts and alkaline-earth metal salts thereof, ora thio analog of any of these.

Aithough useful electronically conducting compositions can be prepared in accordance with the method of 60 the invention comprising a polypyrrole or a co-polymer of a pyrrole, and a low mobility anion as described 60 above, the properties ofthe compositions may be improved by the inclusion of other components which provide certain desirable properties. The electrolytic baths useful in the formation ofthe compositions of this invention preferbly will contain a plasticizer. Plasticizers are compounds known in the art which have the ability when incorporated into polymeric compounds such as polypyrrole or co-polymers of a pyrrole to 65 increase stretch elongation and/or decrease the modulus ofthe polymer and/or increase flexibility. The last 65

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criterion has been used to define the term plasticizer as applied to the materials in this application. Compounds which can increase the flexibility ofthe compositions ofthe invention generally are included in the electrolytic baths. In some instances, the low mobility anions which are incorporated into the compositions ofthe invention have more than onefunction and may, for example, include thefunction of a plasticizer 5 and/or a surface active agent in the composition. For example, many ofthe higher molecular weight sulfates 5 or sulfonates listed above as low mobility anions, also function as plasticizers and, additionally, can modify the wetting properties ofthe polymer. A specific example is sodium lauryl sulfate which functions as a low mobility anion and as a plasticizerfor polypyrrole and co-polymers of pyrrole.

The plasticizers which are useful in the present invention include organic sulfates or sulfonates such as 10 alkyl, aryl, arylalkyl, alkaryl and polyolefin sulfates or sulfonates of the types listed above as low mobility 10

anions. Another class of compounds useful as plasticizers and the compositions ofthe present invention are polyhydroxy compounds.

The polyhydroxy compounds are preferably those containing from 2 to 6 alcoholic radicals of which at least 1 is unsubstituted. The unsubstituted polyhydric alcohols include ethylene glycol, 1,2-propylene glycol, 15 1,3-propylene glycol, glycerol, erythritol, pentaerythritol, arabitol, adonitol,xylitol, mannitol, sorbitol,and 15 • neopentylglycol. Higher molecular weight polyhydric alcohols are also useful. Examples of such alcohols include various polyethylene glycols, and polypropylene glycol.

Partially acylated polyhydric alcohols likewise are contemplated for use herein. The partially acylated polyhydric alcohols are preferably those containing from 2 to 6 alcoholic radicals of which at least one but not all 20 are acylated with an aliphatic carboxylic acid having from about 8 to about 30 carbon atoms. Examples are 20 glycerol mono-oleate, glycerol di-stearate, soritan mono-stearate, sorbitan di-decanoate, sorbitan tri-stearate, sorbitan dibehenate, erythritol mono-oleate, 1,1,1 -trimethylol propane mono-myristate, pentaerythritol di-linoleate, ribitol mono-(9,10-dichloro stearate), sorbitan mono-oleate, etc.

The polyhydric alcohols may also contain ether linkages within their molecular structure. The ether-25 containing polyhydric alcohols may be obtained by dehydrating a polyhydric alcohol. Examples of such 25

derivatives are sorbitan and mannitan. The ether-containing polyhydric alcohols may also be obtained by reacting a polyhydric alcohol with an epoxide. The expoxides areforthe most part hydrocarbon epoxides and substantially hydrocarbon epoxides. The hydrocarbon epoxide may be an alkylene oxide or an aryl-alkylene oxide. The aryl-alkylene oxides are exemplified by styrene oxide, para-ethylstyrene oxide and para-30 chlorostyrene oxide. The alkylene oxides include principally the lower alkylene oxides such as ethylene 30

oxide, propylene oxide, 1,2-butene oxide and 1,2-hexene oxide. The substantially hydrocarbon epoxides may contain polar substituents. The polar substituent is usually a halo radical suchaschloro,fluoro,bromo,

or iodo; and ether radical such as methoxy or phenoxy; or an ester radical such as carbomethoxy. Examples of such epoxides are epichlorohydrin and butyl, 9,10-epoxy-stearate. The number of ether linkages in the 35 product is determined by the amount of epoxide added. Thus it is possible to react polyhydric alcohol such as 35 sorbitol with 1,2,3 or more equivalents of an epoxide such as propylene oxide.

The polyhydric alcohols contemplated for use in this invention may also be ether-containing acylated polyhydric alcohols. These may be prepared by a number of methods. A polyhydric alcohol may be dehydrated and subsequently acylated or an alcoholic radical may be acylated first followed by dehydration or other 40 alcoholic radicals. As mentioned previously, the ether linkage may also be introduced by the reaction of an 40 epoxide with the polyhydric alcohol either before or after acylation. Examples of ether-containing acylated polyhydric alcohols include polyoxyethylene sorbitan mono-oleate, polyoxyethylene sorbitan tri-stearate, polyoxyethylene glycerol di-stearate, polyoxypropylene sorbitan di-linoleate, and polyoxypropylene pentaerythritol mono-oleate.

45 A particularly preferred example of a class of plasticizers useful in the compositions ofthe invention are 45 polyalkylene polyols, polyethers and polyglycerols, and particularly polyalkylene glycols wherein the monomer unit may contain from 1 to about 4 carbon atoms and preferably about 2 carbon atoms. Aspecific example is polyethylene glycol. The molecular weight of the plasticizers may vary over a wide range depending upon the composition to be modified and the properties which are to be modified by inclusion ofthe 50 plasticizer. Polyethylene glycols of molecular weight of from about 300 to about 5,000,000 are included in the 50 electrolytic bath composition and are useful in modifying the properties ofthe compositions ofthe present invention.

It also has been discovered that when the electropolymerization of pyrrole or polymerizable mixtures of pyrrole is carried out using either an aqueous medium or a multi-phase system as described below, the 55 presence of polyethylene glycol over a range of molecular weights confers mechanical strength andf lex- 55

ibilityto the polymeric compositions obtained. Moreover, when polyethylene glycol of various molecular weights is added to electrolytic baths ofthe invention, the morphology ofthe polymeric composition obtained generally can be modified by varying the molecular weight ofthe glycol added.

The amount of plasticizer included in the electrolytic bath ofthe invention may vary over a wide range, 60 particularly if the low mobility anion also functions as a plasticizer. Generally, however, the electrolytic bath 60 compositions of the invention will contain less than about 75% of plasticizer and preferably, less than about 25% by weight ofthe plasticizer based on the total weight ofthe bath composition.

The compositions useful in the preparation of the compositions ofthe invention also may contain redox species. Redox species are chemical species that are able to undergo changes in oxidation state and can be 65 oxidized or reduced at an electrode. In this context, the species should generally be reduced before or during 65

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the reduction ofthe polymer beyond that required to change the oxidation state of polymer alone, and,

therefore, stores additional charge. The oxidation and reduction of this species may or may not be reversible. The incorporation of redox species having suitable redox potentials into the compositions ofthe invention generally results in an increase in the charge capacity ofthe composition. Charge capacity of a polymer 5 composition is the total charge consumed per unit mass when the material is oxidized or reduced usually 5

expressed incoulombs/g or ampere hours/kg. Examples of the redox species which are useful include transition metal complexes and more preferably anionictransition metal complexes. Examples of complexes include halide complexes, amine complexes wherein the amine may have the formula-NR5R6R7 wherein each R5, R6 and R7 independently may be hydrogen or an alkyl or an aryl group; oxy complexes such as 10 molybdates, tungstates, vanadates; cyanide complexes such as hexacyanide complexes of transition metals, 10 iron cyanides, cobalt cyanides and molybdenum cyanide complexes. Other redox species which are useful include nitroprussides, polysulfides, transition metal oxy compounds,sulfur compounds or chalcogenides.

The redox species may be included in ionic form in the compositions ofthe invention up to about 70% by weight based on the weight of the total composition. Preferably, redox species are incorporated in anionic 15 form up to the amount necessary to neutralize the charge on the polymer backbone. 15

Surface active agents, also variously referred to as wetting agents or emulsifying agents, may be included in the compositions ofthe invention and in the electrolytic baths utilized to form the compositions ofthe invention. The surface active agent may be hydrophilic or hydrophobic. Typically, the surfactant is a hydro-philic surfactant, and generally, has an HLB (hydrophilic-lipophilic balance) in the range of about 10 to about 20 20. 20

The surfactant can be ofthe cationic, anionic, non-ionic or amphoterictype. Many such surfactants of each type are known to the art. See,forexample, McCutcheon's "Detergents and Emulsifiers", 1978, North American Edition, published by McCutcheon's Division, MC Publishing Corporation, Glen Rock, New Jersey, U.S.A., particularly pages 17-33 which are hereby incorporated by reference fortheir disclosures in this 25 regard. 25

Anionic surfactants contain negatively charged polar groups while cationic surfactants contain positively charged polar groups. Amphoteric surfactants contain both types of polar groups in the same molecule. A general survey of useful surfactants is found in Kirk-Othmer Encyclopedia of Chemical Technology, Second Edition, Volume 19, page 507 and following (1969, John Wiley and Son, New York) and the aforementioned 30 compilation published underthe name of McCutcheon's. These references are both hereby incorporated by 30 reference fortheir disclosures relating to cationic, amphoteric and anionic surfactants. The anionic or non-ionic surfactants are preferred. The low mobility anion incorporated into the polymer may additionally perform the function of a surface active agent.

Among the useful anionic surfactant types are the widely known metal carboxylate soaps, organo sulfates, 35 sulfonates, sulfocarboxylicacidsandtheir salts, and phosphates. Useful cationic surfactants include nitro- 35 gen compounds such as amine oxides and the well known quaternary ammonium salts. Amphoteric surfactants include amino acid type materials and similartypes. Various cationic, anionic and amphotericdis-persants are availabiefrom the industry particularly from such companies as Rohm and Haas and Union Carbide Corporation. Among the non-ionic surfactants are the alkylene oxide-treated products, such as 40 ethylene oxide-treated phenols, alcohols, esters, amines and amides. Ethylene oxide/propylene oxide block 40 co-polymers are also useful non-ionicsurfactants. Glycerol esters and sugar esters are also known to be non-ionic surfactants. A typical non-ionic surfactant class useful with the derivatives ofthe present invention are the alkylene oxide-treated alkyl phenols such as the ethylene oxide alkyl phenol condensates sold by the Rohm & Haas Company. A specific example of these is Triton X-100 which contains an average of 9-10 45 ethylene oxide units per molecule, has an HLB value of about 13.5 and a molecular weight of about 628. Many 45 other suitable non-ionicsurfactants are known; see, for example, the aforementioned McCutcheon's as well as the treatise "Non-ionic Surfactants" edited by Martin J. Schick, M. Drekker Co., New York, 1967, which is hereby incorporated by reference for its disclosures in this regard.

Further information about anionic and cationic surfactants also can befound in the texts "AnionicSur-50 factants". Parts II and lll,edited by W.M. Linfield, published by Marcel Dekker, Inc., New York, 1976,and 50

"Cationic Surfactants", edited by E. Jungermann, Marcel Dekker, Inc., New York, 1976. Both of these references are incorporated by reference fortheir disclosures in this regard.

The electronically conducting polypyrrole orco-polymers of pyrrole ofthe present invention are prepared by electropolymerization of a pyrrole or a co-polymerizable mixture containing a pyrrole at an electronically 55 conductive surface in an electrolytic bath. The electrolytic bath contains a pyrrole or mixture of pyrrole and 55 co-polymerizable monomer, at least one electrolyte salt which includes an anion which will be incorporated into polymer upon formation and at least one liquid in which the pyrrole (and/or co-polymer) and electrolyte salttogether have some finite solubility. The bath may additionally contain a second non-miscible liquid ora gas orfinely divided solid particles or combinations thereof. In one embodiment, the electrolytic bath com-60 prises a pyrrole or co-polymerizable mixture of pyrrole and water. In another embodimentthe electrolytic 60

bath comprises the pyrrole or co-polymerizable mixture of pyrrole and an organic diluent. In yet another embodimentthe electrolytic bath comprises the pyrrole or co-polymerizable mixture containing pyrrole,

water, and a non-miscible liquid such as an organic diluent. The last embodiment wherein the bath contains water and a non-miscible organic diluent, hereinafter referred to as the two-phase system, is useful in prepar-65 ing compositions ofthe invention which may be characterized as being porous and having very high 65

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surface areas.

The electropolymerization of a pyrrole or a co-polymerizable mixture containing a pyrrole utilizing a two-phase system such as water and an organic diluent comprises the steps of

A. immersing an electronically conductive surface in an electrolytic bath comprising at least one liquid and 5 at least one non-miscible liquid wherein the pyrrole or co-polymerizable mixture is one ofthe liquids or is disolved in at least one ofthe liquids and

B. passing an electric current through said bath at a voltage sufficient to electropolymerize the pyrrole or co-polymerizable mixture containing a pyrrole at the electronically conductive surface. Preferably, one ofthe liquids is water and the non-miscible liquid is an organic diluent. Examples of organic diluents useful in the

10 present invention include organic hydrocarbons such as aliphatic or aromatic hydrocarbons, halogenated aliphatic or aromatic compounds, etc. Specific examples include mineral spirits, hexane, heptane, toluene, xylene, 1,2-dichloroethane, dichloromethane, carbon tetrachloride, and chlorobenzene.

The amount ofthe pyrrole or co-polymerizable mixture containing pyrrole in the electrolytic bath may vary over a wide range although the total amount must exceed the amount necessary to form the total amount of 15 polymer desired. The amount ofthe pyrrole dissolved in the electrolyte solution component(s) ofthe electrolytic bath must be enough to permit a reasonable rate ofthe reaction. This amount will usually varyfrom about 10"3 molar up to saturation ofthe electrolyte(s). The amount of electrolyte salt in the electrolytic bath must be sufficient to both conduct the current desired and provide sufficient anionic species for incorporation into the polymer for the purpose of charge neutralization. Typical concentrations are from 10"2 molar up 20 to saturation ofthe bath, and more typically 5 x 10"2upto1 molar in at least one phase.

As mentioned above, the electrolytic bath ofthe invention may contain other ingredients which provide desirable properties to the compositions ofthe invention. Thus, the bath may contain low mobility anions, plasticizers, redox couples, surfactants, etc., as defined above. When an aqueous system or a multi-phase system containing water is utilized forthe electrolytic bath, an emulsifier or emulsion stabilizer may be 25 included to stabilize this system.

The emulsifier may be an aliphatic glycol or a mono-aryl ether of an aliphatic glycol. The aliphatic glycol may be a polyalkylene glycol. It is preferably one in which the alkylene radical is a lower alkylene radical having from 1 to 10 carbon atoms. Thus, the aliphatic glycol is illustrated by ethylene glycol,trimethylene glycol, propylene glycol, tetramethylene glycol, 1,2-butylene glycol, 2,3-butylene glycol, tetramethylene 30 glycol, hexamethylene glycol, orthe like. Specific examples ofthe ethers include monophenyl etherof ethylene glycol, mono-(heptylphenyl) ether oftriethylene glycol, mono-(alphaoctyl-beta-naphthyl) ether of tetrapropylene glycol, mono-(polyisobutene(molecular weight of 1000)-substituted phenyl) ether of octa-propylene glycol, and mono-(o,p-dibutylphenyl) ether of polybutylene glycol, mono-(heptylphenyl) ether of trimethylene glycol and mono-(3,5-dioctylphenyl) ether of tetra-trimethylene glycol, etc. The mono-aryl 35 ethers are obtained by the condensation of a phenolic compound such as an alkylated phenol or naphthol with one or more moles of an epoxide such as ethylene oxide, propylene oxide, trimethylene oxide, or 2,3-hexylene oxide. The condensation is promoted by a basic catalyst such as an alkali or alkaline earth metal hydroxide, alcoholate, or phenate. The temperature at which the condensation is carried out may be varied within wide ranges such as from room temperature to about 250°C. Ordinarily it is preferably 50-150°C. More 40 than one mole ofthe epoxide may condense with the phenolic compound so that the product may contain in its molecular structure one or more ofthe radicals derived from the epoxide. A polar-substituted alkylene oxide such as epichlorohydrin or epibromohydrin likewise is useful to prepare the mono-aryl ether product and such product likewise is useful as an emulsifier.

Likewise useful as the emulsifiers are the mono-ordi-alkyl ethers ofthe aliphatic glycols in which thealkyl 45 radical preferably has 2 to 20 carbon atoms (e.g., octyl, nonyl, dodecyl, behenyl, etc). The fatty acid esters of the mono-aryl or mono-alkyl ethers of aliphatic glycols also are useful. The acids include, e.g., aceticacid, formic acid, butanoic acid, hexanoic acid, oleic acid, stearic acid, behenic acid, decanoic acid, iso-stearic acid, linolenic acid, as well as commercial acid mixtures such as are obtained by the hydrolysis of tall oils, sperm oils, etc. Specific examples are the oleate of mono-(heptylphenyl) ether of tetraethylene glycol and the ace-50 tateof mono-(polypropene (having molecular weight of 1000)-substituted phenyl) ether of tri-propylene glycol.

The alkali metal and ammonium salts of sulfonic acids likewise are emulsion stabilizers. The acids are illustrated by decylbenzene sulfonic acid, di-dodecylbenzene sulfonic acid, mahogany sulfonic acid, heptyl-benzene sulfonic acid, polyisobutene sulfonic acid (molecular weight of 750), and decyl naphthalene sulfonic 55 acid, and tri-decylbenzene sulfonic acid. The salts are illustrated by the sodium, potassium or ammonium salts of the above acids.

Emulsifiers include phosphatides, expecially those having the structural formula

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H

H—C—0—G 5 H—C—0—G

I

H—C—0—G

I

H

10

wherein G is selected from the class consisting of fatty acyl radicals and phosphorus-containing radicals having the structural grouping

0 R"

15 II I

—P—O-R'-N—OH

O R'"

20 wherein R' is a lower alkylene radical having from 1 to about 10 carbon atoms and R"and R"' are lower alkyl radicals having from 1 to 4carbon atoms, and at least one but no more than two ofthe G radicals being said phosphorus-containing radicals. The fatty acyl radicals are forthe most part those derived from fatty acids having from 8 to 30 carbon atoms in the fatty radicals such as octanoic acid, stearic acid, oleic acid, palmitic acid behenic acid, myristic acid, and oleostearic acid. Especially desirable radicals are those derived from 25 commercial fatty compounds such as soyabeam oil, cotton seed oil, and castor seed oil. A particularly effective phosphatide is soyabean lecithin which is described in detail in Encyclopedia of Chemical Technology, KirkandOthmer, volume 8, pages 309-326 (1952).

Also useful as supplementary emulsion stabilizers are the neutral alkali metal salts of fatty acids having at least 12 aliphatic carbon atoms in thefatty radical. These fatty acids include, principally, lauric acid, stearic 30 acid, oleic acid, myristic acid, palmitic acid, linoleic acid, linolenic acid, behenic acid, ora mixture of such acids such as are obtained from the hydrolysis of tall oil, sperm oil, and other commercial fats.

Only a small amount ofthe stabilizer is necessary forthe purpose. It may be as little as 0.01 part and seldom exceeds 2 parts per 100 parts by weight of the electrolytic bath. In most instances it is within the rangefrom 0.1 to 3 part per 100 parts of the bath.

35 As mentioned, the electropolymerization process utilized in this invention can be carried out in an organic diluent and more particularly in an organic phase containing less than about 3% and more preferably less than about 1% of water. Examples of organic diluents include polyols, organic carbonates, ethers, nitriles, etc. It is essential that the solvent does not undergo competitive oxidation during the electropolymerization and thus interfere with the polymerization or substantially reduce the current efficiency ofthe polymerization 40 process.

A preferred embodiment ofthe present invention, however, is the electropolymerization of pyrroles from aqueous media, either a single-phase aqueous system ora multi-phase aqueous sytem. Many ofthe advantages of using aqueous systems are apparent including, reduced costs, availability and easy purification of water, the ability to utilize a wide range of ionic materials as electrolyte salts in water, the ability to utilize high 45 concentrations of ionicspecies thus permitting high electrochemical currents and high polymerformation rates. Under controlled conditions, intact homogeneous films of polypyrroles can be formed on a variety of substrates in aqueous media. Thicknesses rangefrom less than 100 Angstroms to a few millimeters for more dense materials. In some instances, current density has an effect on the morphology. The morphology ofthe electropolymerized compositions ofthe invention can be further modified by the use ofthe additives already 50 discussed.

It has been observed that improved results are obtained when the electroplating bath is thoroughly agitated during the electropolymerization ofthe monomers. Agitation can be accomplished by any known technique including vigorous stirring with paddle mixers, magnetic stirrers, ultrasonics, vibration or by bubbling gases through the bath to provide sufficient agitation (including gases generated at the counter-electrode). 55 Electropolymerization is accomplished by passing an electric currentthrough the bath at a voltage which is sufficient to electropolymerize the pyrrole or co-polymerizable mixture containing a pyrrole at an electronically conductive surface immersed in the electrolytic bath. The electric current may be a continuous electric current or a varying electric current such as a pulse current. Gennerally, the electric current is direct current although in some instances alternating current may be useful.

60 The voltage at the anode should be sufficientto oxidize monomer without producing significant changes in the bath, such as degradation of a bath component, which would adversely affect the polymerization. Generally, current densities of up to two amperes per square centimeter may be used, but preferably, current densities not exceeding 500 milliamperes per square centimeter are utilized. In more preferred embodiments, the current density will be less than 250 and more generally, less than lOOmilliamps persquare 65 centimeter.

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At the above current densities, the pyrrole or co-polymerizable mixture of a pyrrole is electropolymerized at the electronically conductive surface. Depending upon the specific ingredients in the plating bath, the electropolymerizable polypyrrole may eitherform as a powder at the electronically conductive surface and fall into and be dispersed in the electrolytic bath, or alternatively, be deposited on the conductive surface. The 5 deposit may be in the form of a film which is either smooth and dense or irregular with less than the bulkor theoretical density. Bulkortheoretical density ofthe polymers is the density of continuous, pure polymer containing no voids, pores, cavities or inclusions. The bulk or theoretical density can usually be determined by flotation methods. Examples of irregular deposits include porous films, powders, dendriform materials, etc. The nature ofthe cation(s) as well as that ofthe anion(s) present in the electrolytic bath affects the 10 electropolymerization. The morphology ofthe deposit on the electronically conductive substrate can be controlled and modified by the incorporation in the electrolytic bath of various complexing agents forthe ionic constituents ofthe electrolyte. Examples of materials which function as growth regulators when incorporated into the electrolytic bath include the above-discussed non-ionic plasticizers (e.g. polyalkylene glycol such as polyethylene glycol), cryptands, and commercially available crown ethers such as 12-Crown-4,15-15 Crown-5, and 18-Crown-6 available from Aldrich Chemical Co.

The temperature ofthe electrolytic bath during the electropolymerization process is generally maintained between about 15 to about 50°C, although polymerization proceeds over a much widertemperature range. The reaction is conducted at or about room temperature and preferably underthermostatted conditions.

A variety of electronically conductive substrates that do not undergo competitive oxidation during the 20 electropolymerization can be utilized in the process of the invention. Not all types of metals can be used with the entire range of bath formulations. For example, although steel surfaces are useful for electropolymeriz-ing pyrrole in the presence of sodium lauryl sulfate and water, the electrolytic bath containing pentaerythrityl tetrasulfate and water will not deposit a satisfactory film on steel, but deposits a satisfactory coating on nickel substrates. The choice of particular substrate material can be readily determined by those skilled in the art, 25 with a minimum of experimentation. The size and shape ofthe substrate utilized in the process of the invention will vary depending upon the type of cell in which the electropolymerization process is conducted and on the desired form ofthe polymer. For example, when flat films are desired, the substrate will be in a shape of a flat panel in a parallel plate cell.

Apreferred embodiment of this invention provides fora rotating cylindrical anode ora moving beltanode 30 from which the polymer is removed in a continuous process. The polymer can also be collected orstripped from a stationary electrode in a continuous manner.

The time required to produce a given quantity orthickness of polymer will depend upon several factors, including the current density, bath temperature, size or physical dimensions ofthe electronically conductive surface and the temperature ofthe electrolytic bath. Moreover, the specifictype of morphology desired will 35 be an important consideration when selecting the values ofthe process variables such as temperatures, current density, time of coating, voltage, etc.

One ofthe advantages ofthe process ofthe present invention, particularly with the aqueous systems ofthe invention, is the ability to produce films of controlled thickness over a wide range of thicknesses, and in particular,films having thicknesses greaterthan 250 micrometers, and in particularthicknesses between a 40 range of 0.5 mm to 2 cm. Many prior art processes have not been developed to the level required to produce anything but thin films (200 micrometers or less).

In the general process ofthe invention, the electronically conductive surfaces are introduced into the electrolytic bath and connected to a current source. The polymer is formed at the anode. The counter-electrode may consist ofthe bath tank or a separate conductive surface(s) may be introduced into theelectro-45 lytic bath. The bath may have a separate compartmentfor the secondary electrode butthe one compartment configuration is preferred.

When the electropolymerization process is completed, the substrate is removed from the electrolytic bath, and the electropolymerized material is mechanically stripped from the surface. This polymer may be washed with water and with various non-aqueous solvents (e.g., ethers, liquid hydrocarbons, etc.) to remove any 50 undesirable deposits contained on or in the material. If the deposited material has not been fully dried, this can be achieved, if desired, by heating the polymer at elevated temperatures, preferably under vacuum. The particulartemperatures will depend upon the nature ofthe pyrrole or co-polymerizable mixture of pyrroles utilized in the process, but will generally be less than 250°C and preferably below 100°C.

As mentioned earlier, the morphology and physical nature ofthe compositions electropolymerized in 55 accordance with the method ofthe invention will be dependent on a variety of factors including the nature of the substrate, solvent, temperature, agitation, current density, electric potential, etc. Continuous films having a density approximately equal to the bulk density of the polymer can be prepared by the process ofthe present invention when single-phase organic or aqueous systems are utilized. When more irregularfilms characterized by low density and high surface area are desired, the multi-phase processes described above, 60 in particular, the two-phase aqueous systems, are advantageous. In one ofthe preferred embodiments, the low mobility anions are incorporated into the compositions ofthe invention by including said anions in the electrolytic baths. When incorporated into the polymeric compositions ofthe present invention, the anions, as mentioned earlier, have low mobilities and are substantially permanently retained in the polymer on reduction and on any subsequent oxidations or reductions.

65 One ofthe unexpected advantages of preparing the pyrrole polymers and co-polymers of the invention

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containing the low mobility anions is the fact that the polymer is able to be discharged and recharged through at least hundreds of cycles. See, for example, Example 21. This is surprising since it might be expected that highly mobile anions would confer the greatest reversibility. The mechanism forthe observed reversibility is not known but is believed to involve forced transport by other ion(s). Such compositions, there-5 fore, are classified as being electrochemically reversible polymers, and they are, therefore, useful in the 5

prepartion of rechargable batteries.

The following examples illustrate the process ofthe invention. Unless otherwise indicated, all parts and percentages are by weight.

Unless otherwise indicated, inthefollowing Examples, electropolymerizations are conducted at 2 amperes 10 for30 minutes using a Hanovia arc-lamp power supply controlled with a Variac. Agitation is accomplished 10 with a horizonal perforated glass disk mounted on the bottom of a stirring rod (about 1 to2cmfromthe bottom ofthe bath) and rapidly vibrated up and down with a Vibro-Mixer (Model E1, supplied by A.G. Fur Chemie-Apparatebau Mannedorf-Zurich). The temperature is controlled with an ice bath. Both electrodes are 15 x 7.5 x 0.05 cm panels of steel (AISI No. 10/10) in parallel plate configuration that have been degreased 15 with toluene. The surface area (one side) of each electrode immersed in the bath is 70 cm2 and the distance 15 between the electrodes is 5.5 cm. The polyethylene glycol used in some ofthe examples has an average molecular weight of about 15-20,000. The bath is exposed to the atmosphere. The descriptions ofthe polymerfilmsof thefollowing Examples do not cover edge effects. These effects produce irregularities which rarely effect more than five percent ofthe total massofthefilm.

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Example 1

In this example, the following components are utilized:

Grams

25 Pyrrole 40 25

Sodium Lauryl Sulfate 40

Polyethylene Glycol 20

Distilled Water 1600

Heptane 200 (ml.)

30 30

Theabovefirstfour ingredients are mixed in a container until homogeneous, and 375 ml. of this mixture is added to the 10.8 x 8.9 x 5.7 cm. reaction vessel. Two steel panel electrodes are put into place. Heptane (50 ml.) is added, and agitation is accomplished mechanically with a Vibro Mixer.

Fourfilms are separately prepared at 2 amperes utilizing a reaction time of 30 minutes. The temperature is 35 controlled with an ice bath and is initially 21°C and rises to a temperature of about 34-37°C during the reac- 35

tion. The current is maintained at 2 amperes, but the voltage changes from about 60 to about 40 volts during the course ofthe reaction. The electrolyte side of each film has a few irregularities in the form of dendriform projections (about 1 millimeter) and these projections are removed by light abrasion before stripping the filmsfrom the electrode surfaces. Each film is rinsed thoroughly in distilled water and in heptane.

40 Two ofthe films are fully dried in a vacuum oven at 50°C for 24 hours. The cleaned films obtained in this 40

manner appear to comprise 3 layers. The first layer which is the layer closest to the steel panel is smooth and continuous. The second layer adjacent to the smooth layer is a uniformly porous material and the third layer adjacent to the second layer is denser and less porous than the second layer. The two other films obtained in this example are stripped of their backing or smooth layer and cut into 3/4 inch strips. The strips are cleaned 45 in a soxhlet extractor with distilled water for 15 hours. After drying at room temperature, the pieces are 45

further dried in a vacuum oven at 50°C for 24 hours.

Example 2

A mixture of 5 grams of pyrrole, 1 gram of sodium ethane disulfonate, 2 grams of polyethene glycol and 50 200 grams ofwater is prepared and addedtoan8 x 7 x 4.5 cm reaction vessel. The cathode is a 15 x 5 x 0.025 50 cm piece of Precision brand shim steel (a product of Precision identified as NIDA/SIDA1613D A1). The anode is a 10 x 5 x 0.05 cm Nickel 200 panel. (Nickel 200 is a product of Inco identified as a high purity nickel.)The surface area (one side) of each electrode immersed in the bath is about 40 cm2. Toluene (20 ml.) is added and the mixture agitated using a Vibro-Mixer. The electropolymerization reaction is conducted for 15 minutes at a 55 constant current of 0.5 amperes at a potential of about 17 volts. The film formed on the electrode is removed 55 and observed to be a relatively porous uniform film of about 0.3 to 0.4 mm in thickness.

Example 3

A mixture of 20 grams of pyrrole, 4 grams of pentaerythrityltetrahydrogensulfate, 4 grams of polyethylene 60 glycol and 800 gramms ofwater is prepared and mixed until homogeneous. A volume of 375 ml. is added to a 60 5.7 x 8.9 x 10.8 cm reaction vessel, and 50 ml. of dichloromethanealso is added to the vessel. In this example, a panel of steel (AISI No. 10/10) (T5 x 7.5 x 0.05 cm) is used as the cathode, and a Nickel 200sheet (14.2 x 7.6 x 0.025 cm) is used as the anode. The electropolymerization is carried out in a normal manner over a period of 15 minutes while maintaining a current of 2 amperes. A porous mass of approximately 1 cm 65 in thickness with a low density (less than 0.1 g cm"3) is obtained; this porous mass is electronically conducting. 65

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Example 4

A mixture of 20 grams of pyrrole, 10 grams of sodium-1,10-decane disulfonate, 10 grams of polyethylene glycol and 800 parts ofwater is prepared, and 375 ml. added to each of two reaction vessels. Heptane (50 ml.) is added to each reaction vessel, and the electropolymerization carried out in the normal manner at a current 5 of 2 amperes. The electropolymerization in thefirst reaction vessel is terminated after 5 minutes yielding a thin black tlectronically conductive film covered with small dendriform projections of about 1 mm. in height.

The electropolymerization reaction in the second vessel is carried out for 39 minutes yielding a thicker base film covered with small dendriform projections of approximately the same dimensions as forthe previous film.

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Example 5

A mixture of 10 grams of pyrrole, 10 grams of sodium lauryl sulfate and 0.5 grams of polyethylene glycol is prepared and added to the reaction vessel. In this example, both electrodes are steel panels and agitation is accomplished with a Vibro Mixer. The electropolymerization reaction is conducted for 20 minutes at a current 15 of 2 amperes. A thick rather uniform coating is deposited on the anode and the coating is covered with small dendriform shapes which are easily removed by light abrasion.

Example 6

The procedure of Example 5 is repeated except that 50 ml. of heptane is added to the mixture in the reaction 20 vessel, and the electropolymerization is conducted for five minutes at 2 amperes. The film prepared in this manner is more porous than the material obtained from the procedure of Example 5 and is covered with dendriform shapes.

Example 7

25 Pentaerythrityl tetrasulfate ammonium salt is prepared from pentaerythritol and sulfamic acid in N,N-dimethylformamide. A mixture of 5 grams of pyrrole and 5 grams ofthe ammonium salt in 200 ml. water is prepared and electropolymerized in a 8 x 7 x 4.5 cm reaction vessel wherein the cathode is a 15 x 5 x 0.025 cm Precision brand steel sheet and the anode is a 6.4 x 5 x 0.025 cm nickel sheet. About 40 cm2 ofthe nickel sheet is immersed in the bath. The distance between electrodes is4.5 centimeters. Electropolymerization is 30 conducted at a current of 0.3 amperes for a period of 10 minutes yielding a black electronically conducting film characterized by a somewhat rough surface on the solution side of thefilm.

Example 8

The procedure of Example 7 is repeated except that 2 grams of polyethylene glycol is included in the 35 mixture contained in the reaction vessel. The black electronically conducting film obtained in this manner is more uniform and smoother on the solution side than thefilm obtained in Example 7.

Example 9

Mannityl hexasulfate ammonium salt is prepared from mannitol and sulfamic acid indimethylformamide. 40 A mixture of 5 grams of pyrrole and 1 gram of this ammonium salt is dissolved in 200 ml. ofwater. Utilizing the apparatus described in Example 7, the electropolymerization is carried out at a current of about 0.4 amperes over a period of 20 minutes. The product is a black electronically conducting film which is shiny on the substrate side and rough on the solution side.

45 Example 10

The procedure of Example 9 is repeated except that 2 grams of polyethylene glycol is added to the mixture in the reaction vessel. A more uniform film is obtained in this example which is much smoother on the solution side.

50 Example 11

A mixture of 15 grams of pyrrole in 500 grams ofwater is prepared, and a second mixture of 10 grams of potassium ferricyanide and 5 grams of polyethylene glycol is prepared in 400 ml. ofwater. The two solutions are mixed together and shaken. Approximately 450 ml. ofthe mixture is poured into the 10.8 x 8.9 x 5.7 cm reaction vessel. The electrodes used in this example are both steel panels. The electropolymerization is 55 conducted at 5 amperes. At the start ofthe reaction the temperature is 23°C and the voltage is 22 volts. During the electropolymerization reaction, the temperature is stabilized at 31 -32°C with an ice bath. At this temperature, 20 volts is required to maintain a current of 5 amperes. The distance between electrodes is 5.5 cm. The electropolymerization reaction is conducted for 40 minutes. The polymer is then removed from the anode. This film is 0.8 mm. thick, black and electronically conducting. The film is smooth on both sides 60 although smoother on the substrate side.

Example 12

The procedure of Example 11 is repeated except that the 15,000-20,000 molecular weight polyethylene glycol is replaced by an equivalent weight of Carbowax4000 (a product of Union Carbide identified as 4,000 65 molecular weight polyethylene glycol). The electropolymerization reaction is conducted at 5 amperes current

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and about 20 volts are required to maintain this currentthroughoutthe 40 minute reaction period. The temperature ofthe bath ranges from 22° to 32°C. The polymer is removed from the electrode, and thefilm obtained in this manner is black and electronically conducting. The substrate side is smooth while thesol-ution side is covered with dendriform structures.

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Example 13

A mixture of 2 grams of pyrrole, 0.4 grams of a 50% aqueous solution ofthe sodium salt of 2-acrylamido-2-methylpropanesulfonic acid and 100 ml. ofwater is prepared and mixed until homogeneous. In this example, the cathode ofthe reaction vessel is a platinum strip (0.5 x 3 cm.) and the anode is a gold surface (2 x 4cm) 10 with about 4 cm2 immersed in the bath. The electrodes are rinsed with distilled water priorto use. The electropolymerization in this example is carried out using a Hewlett Packard power supply/amplifier Model 6824A. The electropolymerization reaction is conducted at a current of 24 milliamps and at a voltage of 15 volts for a period of 2 minutes. A thin black electronically conductive film is deposited on the gold surface.

15 Example 14

The procedure of Example 13 is repeated except that the electrolyte salt utilized ispoly(2-acrylamido-2-methylpropanesulfonicacid sodium salt having an inherent viscosity of 0.1 dl. g."1 (measured in 0.5 N NaCI at 30°C). The electropolymerization is conducted at 30 milliamps at 20 volts for a period of 2 minutes. Asmooth thin glossy black electronically conducting film is deposited on the gold surface.

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Example IS

A mixture of 20 grams of pyrrole, 20 grams of sodium lauryl sulfate, 10 grams of polyethylene glycol and 800 grams ofwater is prepared, and 375 ml. of this mixture is added to the 10.8 x 8.9 x 5.7 cm reaction vessel. Heptane (50 ml.) for each experiment) is then added to the reaction vessel, and agitation is accomplished with 25 a rapidly vibrating glass disk. The temperature is controlled with an ice bath. In this example, the electropolymerization is carried out using a current of 2 amperes. The reaction time is 30 minutes and the reaction temperature ranges from 20°-38°C. The polymerformed on the anode is removed and cleaned by washing several times in distilled water. The film prepared in this manner comprises a very thin base layer nextto the substrate, a uniformly porous layer adjacent the base layer and a denser wrinkled less porous layer on the 30 electrolyte side. The polymer layer is removed from the electrode and a 4 x 1 cm strip is cut from the film and its thin base layer is removed. The rest ofthefilm is broken into pieces and rinsed several times with distilled water along with the strip. The pieces and the strip are then rinsed further in a Soxhlet extractor using distilled wat'erfor 15 hours (about 40 extractions). The materials are then dried in a vacuum oven at 80°Cfor 29 hours. This polymer is electronically conducting and can be ground dry to a porous powder which iseasily 35 cold pressed without any additives into various shapes as desired. The shapes obtained in this manner are also electronically conducting.

Example 16

The procedure of Example 15 is repeated except that the mixture contains only 7.5 grams of polyethylene 40 glycol. The electropolymerization ofthe mixture results in a thinner, denserfilm than obtained in Example 15. The film also does not appearto be as flexible and the corresponding powder does not cold press as well as the powder obtained in Example 15.

Example 17

45 The procedure of Example 15 is repeated except thatthe mixture contains only 5 grams of polyethylene glycol. Thefilm obtained in this manner is electronically conductive, is thinner than thefilm obtained in Example 16 and is less uniform.

Example 18

50 A mixture of40 grams of pyrrole, 40 grams of sodium lauryl sulfate, 15 grams of polyethylene glycol and 1,600 grams ofwater is agitated until homogeneous, and 1200 ml. is added to a 8.25 x 14 x 19 cm plastic reaction vessel. Both electrodes are 14 x 19 x 0.1 cm panels of steel (AISI No. 10/10) steel plate degreased with toluene. Heptane (150 ml.) is added and agitation is accomplished with a Vibro Mixer. The surface area ofthe anode covered with polymer is about 250 cm2. The electropolymerization reaction is conducted for a 55 period of one hour at a current of about 4 amperes D.C. The product is removed from the anode and partially pulverized by hand while washing with distilled water. Afterfurther washing (Soxhlet extraction with distilled water) and drying, (vacuum oven,85°C, 20 hr.) the polymer was pulverized further with a mortarand pestal. In this manner, fine black electronically conducting powder is obtained.

The powder obtained in this example can be cold pressed at room temperature in the dry state without any 60 additives, and the pressed electrodes obtained in this manner exhibit improved electronic conductivity over the dried electropolymerized films. The density ofthe electropolymerized film is about 0.2 g cm"3 whereas the density of the pressed electrode is about 0.8 g cm"3.

Example 19

65 The procedure of Example 18 is repeated exceptthatthe power source is a simple full wave rectifier (12

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amp rating) controlled with a Variac. The voltage requirements are essentially identical to those of Example 18.

Example 20

5 An electrolyte bath is prepared comprising 1 g of phenyl phosphonic acid and 2 g of pyrrole in 100gof water. The electropolymerization is carried out in the unstirred bath on a gold strip of dimensions 3 cm x 0.5 cm. The gold strip is immersed to a depth of 1 cm. A platinum counter-electrode is employed and a current of 1 milliampere is maintained for 300 seconds. The product is a black electronically conducting film.

In particularly advantageous embodiments polymers or co-polymers of the invention can be heattreated 10 to enhance their electrochemical storage capacities. Heat treatment is preferably conducted at a temperature above the transition temperature ofthe composition observed during differential scanning calorimetry (DSC) in the region of about 60°C. For example, a temperature in the range of about 60°C up to the decomposition temperature ofthe polymer, preferably about 80°C to about 100°C, can be used. Heat treatment is preferably conducted under a vacuum or partial vacuum (e.g., a pressure of about 1 mm Hg. absolute or less) and is 15 continued until equilibrium is achieved or substantially achieved (e.g., about 10 to about 20 hours).

The electronically conductive polymers or co-polymers prepared in accordance with this invention are useful, for example, for electrodes in electrochemical cells (e.g., as electrodes in batteries, both primary and secondary batteries); as coatings for photocells to inhibit photo-corrosion or corrosion processes;forcata-lytic electrodes; for electric conductors; for conductive substrates and/or binders and mixtures for composite 20 electrodes; for switching devices; and as durable or corrosion resistant electropolymerized coatings. The electronically conductive polymers of the invention are also useful in solid state applications (e.g., in the formation of junctions) and/orfor photovoltaic and photoelectrochemical devices and as reversible electrode materials in electrochemical cells and batteries.

Electrodes produced in accordance with the present invention may be positive or negative and may con-25 tain in addition to polymer, a suitable binder material and/or suitable high surface area carbon materials.

They may also contain at least one other redox species. Suitable binder materials are inert polymeric binders that do not hinder the electrochemical performance ofthe resulting electrode. An example of such a binder material is a halogenated polymeric material such as polytetrafluoroethylene which is preferably introduced from an aqueous suspension, such suspension being available commercially, for example, from DuPont 30 underthe trade designation Teflon T30B. Polytetrafluoroethylene introduced intheform of a powder may be used. Other polymers, for example polypropylene, may be suitablefor use in such compositions under conditions that are not strongly oxidizing. High surface area carbons that are suitable are those materials having surface areas of about 1 to about 2000 square meters per gram, preferably about 60 to about 1200 square meters per gram. Examples of commercially available high surface area carbons that are useful are 35 RB Carbon identified as having a surface area of about 1200 square meters per gram, and Shawinigan Black identified as having a surface area of about 60 to about 65 square meters per gram.

Polymeric electrodes can be prepared in accordance with the invention by mixing a polymer of the invention together with the optional ingredients of binder, high surface area carbon and/or other redoxspecies with water or organic liquid (e.g., mineral spirits) to provide a paste-like mixture. The paste-like mixture is 40 then cold pressed or rolled according to standard techniques preferably at a pressure in the range of about 500 to about 12,000 PSI and a temperature in the range of about room temperature to the decomposition temperature ofthe polymer, to provide an electrode of desired shape. The polymer is preferably heattreated to increase its electrochemical storage capacity priortoorsubsequentto being incorporated into the mixture.

45 The polymeric electrodes provided in accordance with the present invention either as anodic films or pressed from powders are suitable for use in electrochemical cells, particularly electrochemical storage ceils or batteries (both primary and secondary batteries) as the positive and/or negative electrode. These electrodes can have any desired size and shape, such size and shape depending upon the size and shape ofthe electrochemical cell or battery forwhich they are used.

50 In electrochemical cells wherein the polymeric material ofthe invention is the positive electrode, a metal negative electrode can be used. The metal negative electrode is designed and constructed in accordance with standard practice and preferably is an alkali metal or an alkaline-earth metal or an alloy of either. Preferred alkali metals are lithium, sodium and potassium. Preferred alkaline-earth metals are magnesium and calcium. Suitable alloying materials are aluminum and silicon, for example.

55 In electrochemical cells wherein the polymeric material ofthe invention is the negative electrode, the positive electrode can be made of any material (i.e., metal or non-metal) provided such positive electrode is electrochemically more positive than the polymeric negative electrode of the invention.

Both polymeric positive and negative electrodes can be provided in an electrochemical cell in accordance with the present invention. These electrodes may have different compositions or can have the same com-60 position and/or be made in accordance with the same method, provided such electrodes can accomodate sufficiently different charge states to provide an effective electrochemical cell. The polymeric electrodes (negative and positive) provided in accordance with the present invention preferably comprise porous electronically conducting compositions comprising an electropolymerized polypyrrole or co-polymer of a pyrrole having an apparent density of from about 0.1 g cm"3 up to about the bulkdensity ofthe polypyrrole or 65 co-polymer and a surface area of at leasttwo times the surface area of a smooth film of bulk density of the

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composition. These electrodes preferably contain one or more low mobility anions characterized by an average ionictransference number during reduction of less than about 0.1, preferably less than about 0.01. An advantage ofthe positive electrodes comprising the polymers provided in accordance with the present invention is that electronic resistance of such electrodes increases as the discharge voltage ofthe cell app-5 roaches zero volts thus tending to protect the electrochemical cell from damage resulting from over- 5

discharge.

Referring to the drawings, Figure 1 illustrates a laboratory scale flooded lithium cell with an outer large container 1 having a cap 2. The cap 2 is constructed with a hole in the center in which a rubber stopper 3 is inserted. Within the large container 1 is a smallercontainer4 held in place by rubberflange 14. The elements 10 ofthe lithium cell are maintained in the small container4. The larger container 1, cap 2 and stopper3 being 10 utilized to maintain a specific atmosphere such as argon. The desired atmosphere such as argon is introduced through plastic tubing inserted through the stopper as indicated at 10, and the argon exits through tube 11. A strip ofthe polymer ofthe invention 6 is suspended within the inner container 4 using nickel contacts 13, and two lithium electrodes 5 and 9 also are suspended through the stopper 3 into the inner container4 15 through the use of platinum hooks 8. The polymer electrode 6 is a positive electrode whereas lithium elec- 15 trade 5 is a working negative electrode and lithium electrode 9 is a reference electrode. Working electrode 5 is largerthan the reference electrode 9. Sufficient non-aqueous electrolyte 12 is added to the inner container 4 to provide an electrolyte level 15 below the platinum hooks 8 and covering a portion ofthe positive electrode 6 and the two lithium electrodes 5 and 9.

20 The reversible storage of charge in the materials ofthe present invention is also demonstrated in aflooded 20 cell in an argon filled glove box, Figure 2. The glass container 30 holds 50 ml. of non-aqueous electrolyte 31. A strip 32 ofthe polymer ofthe present invention is suspended between strips 33 and 34 of active lithium metal,

and is in electrochemical ionic communication with strips 33 and 34 by means of the electrolyte 31. Lithium electrode 33 is a negative electrode and acts as a source (during discharge) and a sink (during charge) of 25 lithium ions. Lithium electrode 34 is placed in close proximity to the strip 32 and serves as a reference 25

electrode; no currentflows through electrode 34.

When active metals such as lithium, sodium or calcium are used as negative electrodes, non-aqueous electrolytes are used. Typically, these electrolytes are organic liquids which have salts ofthe electroactive species dissolved in them. Forexample, in the case of cells employing lithium negative electrodes, well 30 known electrolytes are used such as propylene carbonate/1.0M lithium perchlorate(PC/1.0M LiCI04),tetra- 30 hydrofu ran/1.5M lithium hexafluoroarsenate, 2Me-tetrahydrofu ran/1.0M lithium hexafluoroarsenate, mixtures thereof, etc.

The present invention also includes primary and secondary batteries, Figures 3 and 4, which include negative alkali metal electrode 45 (e.g., lithium, sodium or potassium); separator46; polymeric positive electrode 35 47 which is prepared in accordance with the present invention; ceramic or glass feed-through insulator49; 35 spacers 50 and 51, and metal negative electrode contact 52. Metallic casing 48 provides containment ofthe cell components and electrical contactto the positive electrode 47. Negative electrode 45 is electronically isolated from the positive electrode contact48 bytheinsulator49. Alternatively, cell containment can be provided by an insulating material such as plastic, and electrical contact can be made to the electrode by 40 means of metallic grids, screens, foils, etc. In a preferred embodiment a cylindrical wrapping ofthe negative 40 electrode 45,separator46, and positive electrode47 into a cell having a spiral-wound configuration is provided.

Another preferred embodiment ofthe present invention, Figure 5, is laboratory-scale electrochemical energy storage cell 60 which has a layered configuration and includes polymeric positive electrode 61 which is 45 prepared in accordance with the present invention, lithium negative electrode 62, lithium reference electrode 45 63, glass fiber separators 64, gold contacts 65,66 and 67, glass plates 68 and 69 and epoxy seal 70. The cell is assembled in dry airorin an inert atmosphere,forexample,argon.

Another preferred embodiment of the present invention includes layered orstacked cell 71 (Figure6) in which a number of positive and negative electrodes are respectively connected in parallel for purposes of 50 increasingthe maximum currentthatcan be supplied bythe resulting battery package. Cell 71 includes 50

parallel spaced polymeric electrodes 72a-d, which are provided in accordance with the present invention, and parallel spaced negative electrodes 73a-d which are parallel to and spaced from electrodes 72a-d. Electrodes 72 and 73 are housed within container 74. Container 74 is preferably electronically insulating. Electrode 73a is positioned in parallel spaced relationship between electrodes 72a and 72b. Electrode 73b is 55 positioned in parallel spaced relationship between electrodes72b and 72c. Electrode 73c is positioned in 55

parallel spaced relationship between electrodes 72c and 72d. Electrode 73d is positioned in parallel spaced relationship below electrode 72d. Electrodes 72a-d are connected to contact 76 which projects from container 74. Similarly electrodes 73a-d are connected to contact 77 which projects from container 74. Separatormat-erial 75, which contains a suitable electrolyte, is dispersed throughout the interior of container 74. Although 60 four electrodes 72a-d and four electrodes 73a-d are shown in the illustrated embodiment, itwill be under- 60

stood by those skilled in the art thatthe number of such electrodes can be fewer or greaterthan four, such number being dependent upon the requirements for cell 71.

In still another embodiment ofthe present invention, layered or stacked cell 81 (Figure 7) is provided in which a series stack of alternating positive and negative electrodes gives a bipolar configuration forthe 65 purposes of increasing the total voltage ofthe resulting battery package. Cell 81 includes parallel spaced 65

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polymeric electrodes 82a-d, which are provided in accordance with the present invention, and parallel spaced negative electrodes 83a-d, which are parallel to and spaced from electrodes 82a-d, respectively. Separators 84a-d which can be made of fibrerglass, for example, and contain a suitable electrolyte are positioned between electrodes 82a-d and 83a-d as shown. Electrodes 82a-d and 83a-d and separators 84a-d are housed 5 within electronically insulating container 85. Container 85 also includes bipolar electronically conductive plates 86,87 and 88 which divide container 85 into four isolated compartments 90,91,92 and 93. Electrodes 82a and 83a, and separator 84a are positioned in compartment 90. Electrodes 82b and 83b and separator84b are positioned in compartment 91. Electrodes 82c and 83c and separator 84c are positioned in compartment 92. Electrodes 82d and 83d and separator 84d are positioned in compartment 93. Contact to the two ends of 10 the series stack is provided by contacts 95 and 96 which project from container 85. Although four electrodes 82a-d and four electrodes 83a-d are shown in the illustrated embodiment, itwill be understood by those skilled intheartthatthe numberof such electrodes can befewerorgreaterthanfour,such numberbeing dependent upon the requirements for cell 81.

15 Example 21

The composition of Example 6 is used as a positive electrode material in lithium cell 60, the design of cell 60 being depicted in Figure 5. The cell 60 is assembled in a dry argon atmosphere. The polymer composition 61 is electropolymerized on a gold strip which serves as contact 65. The thickness of each separator 64 is about 0.5 mm. Separators 64 are soaked with electrolyte, 1M LiCI04 in propylene carbonate. Negative electrode 62 20 and reference electrode 63 are formed from lithium. The cell 60 sandwiched between glass plates 68 and 69 as shown, is clamped together and the edges sealed with epoxy 70.

A thin film of polymer is prepared in accordance with Example 6, with the exception that it is electropolymerized for a shorter time. The film is tested as the positive electrode in ceil 60.

The areal density of the film is about 0.1 mg cm"2. The discharge is carried out at a current of about 0.1 25 mA-cm2, and is terminated when the potential between the positive electrode 61 and the reference electrode 63 drops to about 1 volt. At this point the polymer demonstrates a specific capacity of 19 Ah (kg polymer)"1.

This cell is repeatedly recharged and discharged under constant current conditions, and exhibits good reversibility over more than 200 cycles. The performance of this cell was not degraded despite repeated overdischarging and repeated overcharging on the order ofthe capacity ofthe cell. The open circuit voltage 30 of this type of eel I when tested over a period of four months shows little or no degradation.

Example 22

The composition of Example 11 is used as the positive electrode material in the cell described in Example 21. Athin electropolymerized film of areal density of about 0.25 mg cm"2 is discharged at a current of about 35 0.25 mA cm"2. The discharge is terminated when the potential between the polymer and the reference electrode drops to about 1 volt. This composition exhibits a specific capacity of 83 Ah (kg polymer)"1.

Example 23

A porous composition prepared according to Example 1 is used as the positive electrode material in the cell 40 of Figure 1. The self supporting film has approximate dimensions of 2 x 0.8 x 0.1 cmandaweightofabout48 mg. The discharge is carried out at a total current of 2 miliamperes, and terminated when the overall cell voltage (between electrodes 5 and 6) drops to 1 volt. This material demonstrates a specific capacity of about 35 Ah (kg polymer)"1 andean be charged and discharged in excess of 220cycles.

45 Example 24

The composition produced by the method of Example 15 is used as positive electrode material in thecell illustrated in Figure 2. The negative electrode material is lithium and the electrolyte is 1M LiCI04 in propylene * carbonate. The cell is discharged at a current of 1 mA cm"2 and the discharge is terminated when the overall cell voltage falls to 1 volt. The material demonstrates a reversible specific capacity of 57 Ah (kg polymer)"1.

50

' Example 25

The composition produced by the method in Example 16 is used as positive electrode material in the cell illustrated in Figure 2. The negative electrode material is lithium and the electrolyte is 1M LiCI04 in propylene carbonate. The cell is discharged at a current of 1 mA cm"2 and the discharge is terminated when the overall 55 cell voltage falls to 1 volt. The material demonstrates a reversible specific capacity of 59 Ah (kg polymer)"1.

Exam pie 26

A porous composition prepared according to Example 1 is heattreated at 80°C and a pressure of about 1 mm Hg absolute for 12 hours.

60

Example27

Example 23 is repeated with the exception that the product of Example 26 is used as the positive electrode material in the cell of Figure 1. This material demonstrates a specific capacity of about 57 Ah (Kg polymer)"1.

Whilethe invention has been explained in relation to its preferred embodiments, it isto be understood that 65 various modifications thereof will become apparentto those skilled in the art upon reading the specification.

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Therefore, it is to be understood that the invention disclosed herein is intended to cover such modifications that fall within the scope ofthe appended claims.

Claims (1)

1. 5

   1. An electronically conducting composition comprising electropolymerized polypyrrole ora co-polymer of pyrrole, said composition containing one or more low mobility anions characterized by an average ionic transference numberfor said low mobility anions during reduction of less than aboutO.1.

   2. The composition of claim 1 wherein said composition is heattreatedtoenhancetheelectrochemical

   10 storage capacity of said composition.

   3. The composition of claim 1 wherein said ionic transference number is less than 0.05.

   4. The composition of claim 1 intheform of a homogeneous coherent smooth film of bulk density ora uniformly porousfilm of lessthan bulkdensity.

   5. The composition of claim 1 wherein the anions are derived from organic sulfates orsulfonates.

   15 6. The composition of claim 5 wherein the sulfates orsulfonates are alkyl, aryl, arylalkyl, alkaryl or poly-olefin sulfates or sulfonates, each containing one or more anionic sites.

   7. The composition of claim 1 wherein the anion is an alkyl sulfate containing at least 4carbon atoms in the alkyl group.

   8. The composition of claim 7 wherein the alkyl sulfate is lauryl sulfate.

   20 ' 9- The composition of claim 1 whereintheanionisderivedfromasulfatedpolyhydroxycompound.

   10. The composition of claim 9 where the sulfated polyhydroxy compound is pentaerythrityltetrasulfate salt or corresponding acid.

   11. The composition of claim 1 wherein the anions are derived from pentavalent phosphorous compound.

   25 12. The composition of claim 11 wherein said phosphorous compound is phosphate.

   13. The composition of claim 11 wherein said phosphorous compound is phosphonate.

   14. The composition of claim 11 wherein said phosphorous compound is phosphinate.

   15. The composition of claim 1 also containing at least one plasticizer.

   16. The composition of claim 15 wherein the plasticizer is a polyhydroxy compound.

   30 17. The composition of claim 15 wherein the plasticizer is a polyalkylene glycol.

   18. The composition of claim 1 comprising a redox species.

   19. The composition of claim 18 wherein the redox species is a transition metal complex.

   20. The composition of claim 1 wherein the anion is also a plasticizer for the composition.

   21. A method of preparing electronically conducting polypyrrole or co-polymer of pyrrole which com-

   35 prises the steps of

   A. electropolymerizing a pyrrole or a co-polymerizable mixture containing a pyrrole at an electronically conductive surface in an electrolytic bath by

   1. immersing an electronically conductive surface in an electrolytic bath which comprises an aqueous mixture comprising pyrrole ora co-polymerizable mixture of pyrrole, water, and one or more low mobility

   40 anions which are incorporated into the polypyrrole by electropolymerization and which anions are characterized by an average ionictransference number on reduction of less than 0.1.

   2. agitating the bath, and

   3. passing an electric current through the said bath at a voltage sufficient to electropolymerize the pyrrole or pyrrole mixture and deposit the polymer or co-polymer on the electronically conductive surface, and

   45 B. removing said deposit from the conductive surface.

   22. The method of claim 21 wherein the transfer number change on discharge is less than 0.05.

   23. The method of claim 21 wherein the electrolytic bath is maintained at a temperature of from about 15° to 50°C as the electric current is passed through the bath.

   24. The method of claim 21 wherein the electric current is a direct current.

   50 25. The method of claim 21 with the step of heattreating said electronically conducting polypyrrole or co-polymer of pyrroleto enhance the electrochemical storage capacity thereof.

   26. The method of claim 21 wherein the anions in the bath are derived from organic sulfates orsulfonates.

   27. The method of claim 26 wherein the sulfates or sulfonates are alkyl, aryl, arylalkyl, alkaryl or poly-olefin sulfates orsulfonates, each containing one or more anionic sites.

   55 28. The method of claim 27 wherein the anion is derived from an alkyl sulfate containing at least 4carbon atoms in the alkyl group.

   29. The method of claim 21 wherein the anion is derived from a sulfated polyhydroxy compound.

   30. The method of claim 29 wherein the sulfated polyhydroxy compound is pentaerythrityl tetrasulfate saltorcorresponding acid.

   60 31. The method of claim 21 wherein the anions are derived from pentavalent phosphorous compound.

   32. The method of claim 31 wherein said phosphorous compound is phosphate.

   33. The method of claim 31 wherein said phosphorous compound is phosphonate.

   34. The method of claim 31 wherein said phosphorous compound is phosphinate.

   35. The method of claim 21 wherein the bath also contains a plasticizer.

   65 36. The method of claim 35 wherein the plasticizer is a polyhydroxy compound

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   37. The method of claim 35 wherein the plasticizer is a polyalkylene glycol.

   38. The method of claim 21 wherein the bath comprises a redox species.

   39. The method of claim 38 wherein the redox species is a transition metal complex.

   40. The method of claim 21 wherein the anion also is a plasticizer forthe polypyrrole or co-polymer of 5 pyrrole.

   41. A method of preparing electronically conducting polypyrrole or co-polymer of pyrrole which comprises electropolymerization of a pyrrole or a co-polymerizable mixture containing a pyrrole at an electronically conductive surface in an electrolytic bath by

   A. immersing an electronically conductive surface in an electrolytic bath comprising

   10 (i) a pyrrole or a mixture of a pyrrole with a co-polymerizable monomer,

   (ii) one or more low mobility anions which are incorporated into the polypyrrole or co-polymer of pyrrole and which are characterized by an average ionictransference number of said mobility anions during reduction ofthe polypyrrole or co-polymer of less than 0.1, and

   (iii) an organic diluent, and

   15 B. passing an electric currentthrough said bath at a voltage sufficient to electropolymerize the pyrrole or co-polymerizable mixture containing pyrrole at the electronically conductive suface.

   42. The method of claim 41 wherein the bath is agitated while the electric current is passed through said bath.

   43. The method of claim 41 wherein the polypyrrole or co-polymer of pyrrole is deposited on the conduct-

   20 ivesurface.

   44. The method of claim 41 wherein said transference number is less than 0.05.

   45. The method of claim 41 wherein the bath also contains a neutral or ionic surface active compound.

   46. The method of claim 41 wherein the electrolytic bath is maintained at a temperature of from about 15° to about 50°C as the electric current is passed through the bath.

   25 47. The method of claim 41 with the step of heattreating said electronically conducting polypyrrole or co-polymer of pyrrole to enhance the electrochemical storage capacity thereof.

   48. The method of claim 41 wherein the anions in the bath are derived from organic sulfates orsulfonates.

   49. The method of claim 48 wherein the sulfates or sulfonates are alkyl, aryl, arylalkyl, alkaryl or poly-olefin sulfates or sulfonates, each containing one or more anionic sites.

   30 50. The method of claim 49 wherein the anion is derived from an alkyl sulfate containing at least 4 carbon atoms in the alkyl group.

   51. The method of claim 41 wherein the anion is derived from a sulfated polyhydroxy compound.

   52. The method of claim 51 wherein the sulfated polyhydroxy compound ispentaerythrityltetrasulfate saltorcorresponding acid.

   35 53. The method of claim 41 wherein the anions are derived from pentavalent phosphorous compound.

   54. The method of claim 53 wherein said phosphorous compound is phosphate.

   55. The method of claim 53 wherein said phosphorous compound is phosphonate.

   56. The method of claim 53 wherein said phosphorous compound is phosphinate.

   57. The method of claim 41 wherein the bath also contains a plasticizer.

   40 58. The method of claim 57 wherein the plasticizer is a polyhydroxy compound.

   59. The method of claim 57 wherein the plasticizer is a polyalkylene glycol.

   60. The method of claim 41 wherein the bath comprises a redoxspecies.

   61. The method of claim 60 wherein the redoxspecies is a transition metal complex.

   62. The method of claim 41 wherein the anion also is a plasticizer forthe polypyrrole or co-polymerof

   45 polypyrrole.

   63. An electrochemical cell comprising polymeric electrode means, said polymeric electrode means comprising an electronically conducting composition comprising electropolymerized polypyrrole or a copolymer of pyrrole, said composition containing one or more low mobility anions characterized by an average ionic transference number for said low mobility anions during reduction of less than about 0.1.

   50 64. The cell of claim 63 wherein said transference number is less than 0.05.

   65. The cell of claim 63 wherein said composition is heattreated to enhance the electrochemical storage capacity of said composition.

   66. The cell of claim 63 wherein the anions are derived from organic sulfates orsulfonates.

   67. The cell of claim 66 wherein the sulfates orsulfonates are alkyl, aryl, arylalkyl, alkaryl or polyolefin

   55 sulfates or sulfonates, each containing one or more anionicsites.

   68. The cell of claim 63 wherein the anion is an alkyl sulfate containing at least 4 carbon atoms in the alkyl group.

   69. The cell of claim 68 wherein the alkyl sulfate is lauryl sulfate.

   70. The cell of claim 63 wherein the anion is derived from a sulfated polyhydroxy compound.

   60 71. The cell of claim 70 where the sulfated polyhydroxy compound is pentaerythrityl tetrasulfate salt or corresponding acid.

   72. The cell of claim 63 wherein the anions are derived from pentavalent phosphorous compound.

   73. The cell of claim 72 wherein said phosphorous compound is phosphate.

   74. The cell of claim 72wherein said phosphorous compound is phosphonate.

   65 75. The cell of claim 72 wherein said phosphorous compound is phosphinate.

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   76. The ceil of claim 63 with said composition also containing at least one plasticizer.

   77. The cell of claim 76 wherein the plasticizer is a polyhydroxy compound.

   78. The cell of claim 76 wherein the plasticizer is a polyalkylene glycol.

   79. The cell of claim 63 with said composition comprising a redoxspecies.

   5 80. The cell of claim 79 wherein the redox species is a transition metal complex.

   81. The cell of claim 63 wherein the anion is also a plasticizerforthe composition.

   82. An electrochemical cell comprising polymeric electrode means, said polymeric electrode means comprising electronically conducting polypyrrole or co-polymer of pyrrole prepared by a method which comprises the steps of

   10 A. electropolymerizing a pyrrole or a co-polymerizable mixture of a pyrrole at an electronically conductive surface in an electrolytic bath by

   1. immersing an electronically conductive surface in an electrolytic bath which comprises an aqueous mixture comprising pyrrole or a co-polymerizable mixture of pyrrole, water, and one or more low mobility anions which are incorporated into the polypyrrole by electropolymerization and which anions are char-

   15 acterized by an average ionictransference numberfor said low mobility anions on reduction of less than 0.1,

   2. agitating the bath, and

   3. passing an electric current through the said bath at a voltage sufficient to electropolymerize the pyrrole or pyrrole mixture and deposit the polymer or co-polymer on the electronically conductive surface, and

   B. removing said deposit from the conductive surface.

   20 83. The cell ofthe claim 82 wherein said transference is less than 0.05.

   84. The cell of claim 82 wherein the electrolytic bath is maintained at a temperature of from about 15°to 50°C as the electric current is passed through the bath.

   85. The cell of claim 82 wherein the electric current is a direct current.

   86. The cell of claim 82 wherein said electronically conducting polypyrrole or co-polymer of pyrrole is

   25 heattreated to enhance the electrochemical storage capacity thereof.

   87. The cell of claim 82 wherein the anions in the bath are derived from organic sulfates of sulfonates.

   88. The cell of claim 87 wherein the sulfates orsulfonates are alkyl, aryl, arylalkyl, alkaryl or polyolefin sulfates or sulfonates, each containing one or more anionicsites.

   89. The cell of claim 82 wherein the anion is derived from an alkyl sulfate containing at least 4carbon

   30 atoms in the alkyl group.

   90. The cell of claim 82 wherein the anion is derived from a sulfated polyhydroxy compound.

   91. The cell of claim 90 wherein thesulfated polyhydroxy compound ispentaerythrityltetrasulfatesaltor corresponding acid.

   92. The cell of claim 82 wherein the anions are derived from pentavalent phosphorous compound.

   35 93. The cell of claim 92 wherein said phosphorous compound is phosphate.

   94. The cell of claim 92 wherein said phosphorous compound is phosphonate.

   95. The cell of claim 92 wherein said phosphorous compound is phosphinate.

   96. The cell of claim 82 wherein the bath also contains a plasticizer.

   97. The cell of claim 96 wherein the plasticizer is a polyhydroxy compound.

   40 98. The cell of claim 96 wherein the plasticizer is a polyalkylene glycol.

   99. The cell of claim 82 wherein the bath comprises a redoxspecies.

   100. The cell of claim 99 wherein the redox species is a transition metal complex.

   101. The cell of claim 82 wherein the anion also is a plasticizerforthe polypyrrole or co-polymer of pyrrole.

   45 102. An electrochemical cell comprising polymeric electrode means, said polymeric electrode means comprising electronically conducting polypyrrole or co-polymer of pyrrole prepared by a method which comprises electropolymerization of a pyrrole or a co-polymerisable mixture containing a pyrrole at an electronically conductive surface in an electrolytic bath by

   A. immersing an electronically conductive surface in an electrolytic bath comprising

   50 (i) pyrrole, or a mixture of pyrrole and a co-polymerizable monomer,

   (ii) one or more low mobility anions which are incorporated into the polypyrrole or co-polymer of pyrrole and which are characterized by an average ionic transference numberfor said low mobility anions during reduction ofthe polypyrrole or co-polymer of Jess than 0.1, and

   (iii) an organic diluent, and

   55 B. passing an electric current through said bath at a voltage sufficient to electropolymerize the pyrrole or co-polymerizable mixture containing pyrrole at the electronically conductive surface.

   103. The cell of claim 102 wherein the bath is agitated while the electric current is passed through said bath.

   104. The cell of claim 102 wherein the polypyrrole or co-polymer of pyrrole is deposited on the conductive

   60 surface.

   105. The cell of claim 102 wherein said transference number is less than 0.05.

   106. The cell of claim 102 wherein the bath also contains a neutral or ionic surface active compound.

   107. The cell of claim 102 wherein the electrolytic bath is maintained at a temperature of from about 15°to about 50°C as the electric current is passed through the bath.

   65 108. The cell of claim 102 wherein said electronically conducting polypyrrole or co-polymer of pyrrole is

   5

   10

   15

   20

   25

   30

   35

   40

   45

   50

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   60

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   heat treated to enhance the electrochemical storage capacity thereof.

   109. The cell of claim 102 wherein the anoins in the bath are derived from organic sulfates orsulfonates.

   110. The cell of claim 109 wherein the sulfates or sulfonates are alkyl, aryl, arylalkyl, alkaryl or polyolefin sulfates orsulfonates, each containing oneormoreanionicsites.

   5 111. The cell of claim 110 wherein the anion is derived from an alkyl sulfate containing at least4carbon 5

   atoms in the alkyl group.

   112. The cell of claim 111 wherein the anion is derived from a sulfated polyhydroxy compound.

   113. The cell of claim 112 wherein the sulfated polyhydroxy compound is pentaerythrityl tetrasulfate salt orcorresponding acid.

   10 114. Thecompositionofclaim102whereintheanionsarederivedfrompentavalentphosphorouscom- 10 pound.

   115. The composition of claim 102 wherein said phosphorous compound is phosphate.

   116. The composition of claim 102 wherein said phosphorous compound is phosphonate.

   117. The composition of claim 102 wherein said phosphorous compound is phosphinate.

   15 118. The cell of claim 102 wherein the bath also contains a plasticizer. 15

   119. The cell of claim 118 wherein the plasticizer is a polyhydroxy compound.

   120. The cell of claim 118 wherein the plasticizer is a polyalkylene glycol.

   121. The cell of claim 102 wherein the bath comprises a redoxspecies.

   122. The cell of claim 121 wherein the redox species is a transition metal complex.

   20 123. Thecellofclaim102whereintheanionalsoisaplasticizerforthepolypyrroleorco-polymerof 20

   pyrrole.

   124. An electrochemical cell comprising metal negative electrode means, separator means, electrolyte means, and polymeric positive electrode means, said polymeric positive electrode means comprising a composition comprising electropolymerized polypyrrole or a copolymer of pyrrole, said composition containing

   25 one or more low mobility anions characterized by an average ionictransference numberfor said low mobility 25 anions during reduction of less than about 0.1.

   125. The cell of claim 124 wherein said transference number is less than about 0.01.

   126. The cell of claim 124 wherein said negative electrode means comprises an alkali metal, an alkaline-earth metal, or an alloy of said alkali metal or alkaline-earth metal.

   30 127. The cell of claim 124 wherein said negative electrode means comprises a material selected from the 30 group consisting of lithium, sodium, potassium, magnesium, calcium, or an alloy thereof.

   128. The cell of claim 124 wherein said composition is heattreated to increase its electrochemical storage capacity.

   129. The cell of claim 124 wherein said polymeric positive electrode means provides an enhanced resist-

   35 ivebarrierto damage to said cell arising from overdischarge. 35

   130. The cell of claim 124 wherein said composition is cold pressed to provide said polymeric positive electrode means.

   131. The cell of claim 124 wherein said composition includes binder means, said composition being cold pressed to provide said polymeric positive electrode means.

   40 132. The cell of claim 124 wherein electrical contact is made with said polymeric positive electrode means 40 by screen means or grid means positioned between said polymeric positive electrode means and said separator means.

   133. The cell of claim 124 wherein said polymeric positive electrode means includes at least one other redoxspecies.

   45 134. An electrochemical cell comprising separator means, electrolyte means, polymeric negative elec- 45 trode means, and another electrode means, said another electrode means being more electrochemically positive than said polymeric negative electrode means, said polymeric negative electrode means comprising a composition comprising electropolymerized polypyrrole or a copolymer of pyrrole, said composition containing one or more low mobility anions characterized by an average ionictransference numberfor said low

   50 mobilityanionsduringreductionoflessthanaboutO.1. 50

   135. The cell of claim 134 wherein said transference number is less than about 0.01.

   136. The cell of claim 134 wherein said composition is heattreated to increase its electrochemical storage capacity.

   137. The cell of claim 134 wherein said polymeric negative electrode means provides an enhanced resist-

   55 ivebarrierto damage to said cell arising from overcharging. 55

   138. The cell of claim 134 wherein said composition is cold pressed to provide said polymeric negative electrode means.

   139. The cell of claim 134 wherein said composition includes binder means, said composition being cold pressed to provide said polymeric negative electrode means.

   60 140. Thecellofclaim134whereinelectricalcontactismadewithsaidpolymericnegativeelectrode 60

   means by screen means or grid means positioned between said polymeric negative electrode means and said separator means.

   141. The cell of claim 134 wherein said polymeric negative electrode means includes at least one other redoxspecies.

   65 142. An electrochemical cell comprising: separator means; electrolyte means; polymeric positive elec- 65

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   trode means; and polymeric negative electrode means; said polymeric positive electrode means comprising a first composition; said polymeric negative electrode means comprising a second composition; said first composition and said second composition each comprising electropolymerized polypyrrole or copolymer of pyrrole containing one or more low mobility anions characterized by an average ionictransference number 5 forsaid low mobility anions during reduction of lessthanaboutO.1. 5

   143. The cell of claim 142 wherein said transference number is less than about 0.01.

   144. The cell of claim 142 wherein said first composition and/or said second composition is heattreated to increase its electrochemical storage capacity.

   145. The cell of claim 142 wherein said polymeric positive electrode means provides an enhanced resist-

   10 ive barrierto damage to said cell arising from over discharge, and/or said polymeric negative electrode 10

   means provides an enhanced resistive barrierto damage to said cell arising from overcharging.

   146. The cell of claim 142 wherein said first composition is cold pressed to provide said polymeric positive electrode means and/or said second composition is cold pressed to provide said polymeric negative electrode means.

   15 147. The cell of claim 142 wherein said first composition includes binder means, said first composition 15 being cold pressed to provide said polymeric positive electrode means; and/or wherein said second composition includes binder means, said second composition being cold pressed to provide said polymeric negative electrode means.

   148. The cell of claim 142 wherein electrical contact is made with said polymeric positive electrode means

   20 by screen means or grid means positioned between said polymeric positive electrode means and said separ- 20 ator means; and/or wherein electrical contact is made with said polymeric negative electrode means by screen means or grid means positioned between said polymeric negative electrode means and said separator means.

   149. The cell of claim 142 wherein said polymeric positive electrode means and/or said polymeric nega-

   25 tive electrode means includes at least one other redox species. 25

   150. The invention in its several novel aspects.

   Printed for Her Majesty's Stationery Office by Croydon Printing Company (UK) Ltd, 5/87, D8991685. Published by The Patent Office, 25 Southampton Buildings, London WC2A1 AY, from which copies may be obtained.