WO2018115817A1

WO2018115817A1 - Oligo- or polyether-modified electroactive materials for charge storage devices

Info

Publication number: WO2018115817A1
Application number: PCT/GB2017/053746
Authority: WO
Inventors: Florence BOURCET; Thomas Kugler; Simon King; Jean-Benoit GIGUÈRE
Original assignee: Cambridge Display Technology Limited; Sumitomo Chemical Company Limited
Priority date: 2016-12-22
Filing date: 2017-12-14
Publication date: 2018-06-28
Also published as: GB201621961D0

Abstract

This invention relates to charge storage devices, such as e.g. polymer batteries comprising an electroactive polymer having one or more repeat units, wherein at least one of the repeat units comprises one or more pendant oligo- or polyether groups. The disclosed active material enables enhanced ionic mobility and results in charge storage devices with improved performance which may be manufactured in a simple manner. In another aspect, the present invention describes a method of enhancing migration of ions into a bulk of an electroactive polymer having one or more repeat units by modifying at least one of the repeat units with one or more pendant oligo- or polyether groups.

Description

OUGO- OR POLYETHER-MODIFIED ELECTROACTIVE MATERIALS FOR CHARGE

STORAGE DEVICES

FIELD OF INVENTION

[0001] This Invention relates to charge storage devices, preferably polymer-based batteries which comprise an electroactive polymer having one or more repeat units, wherein at least one of the repeat units comprises one or more pendant oligo- or polyether groups, which results in charge storage devices with improved performance, in addition, the invention relates to a method of enhancing migration of ions into a bulk of an electroactive polymer having one or more repeat units by modifying at least one of the repeat units with one or more pendant oligo- or polyether groups.

BACKGROUND OF THE INVENTION

[0002] In the recent years, there has been a high interest in the development of charge storage devices which exhibit both excellent energy and power density.

[0003] In particular, charge storage devices comprising polymers that can be reversibiy n- doped by means of electrochemistry in use (in the following referred to as "n-type polymers"), and polymers that can be reversibiy p-doped by means of electrochemistry in use (in the following referred to as "p-type polymers") have previously been demonstrated to act as redox-active materials in charge storage devices (see e.g. US 4,442,187 A). In these, they may show properties of both batteries and supercapacitors, depending on a number of factors including the degree of shielding of each charge from the next one along the polymer chain, and the relative mobility of charges and ions within the polymer layers.

[0004] in the last decade, fluorene-based conjugated polymers, such as the homopolymer poly(9,9'-dioctytf!uorene) (PFO) or copolymers with benzothiadiazole (e.g. poly(9,9- dioctytfluorene-a/r-benzothiadiazole (F8BT)) or triarylamines (e.g. F8PFB or F8TFB) have gained increased attention due to their efficient emission performance in optical applications (see e.g. J.-C. Denis, Phys. Chem. Chem. Phys. 2016, 18, 21937-21948).

[0005] However, although fluorene-based conjugated polymers have been demonstrated to exhibit electrochemical activity when provided as thin-films on glassy carbon, batteries based on fluorene-based conjugated polymers such as F8BT as n-type material do not show the expected behavior. For instance, they do not show any battery behavior at all when used in combination with polymer battery current collector materials, such as indium tin oxide (ITO). [0006] These problems are typically addressed by altering the morphology or the physical constitution of the active layer. For example, US 6,096,453 B1 discloses electrochemical energy storage devices, wherein the active polymer layer is modified by forming an organic conjugated compound and an ionically conductive polymer as a bicontinuous interpenetrating network. However, the preparation of such devices is elaborate as it requires a careful selection of additives and extensive analysis and control of the phase distribution.

[0007] In the preparation of light-emitting electrochemical cells it Is known to blend fluorene-based conjugated polymers with a polymer electrolyte such as PEO (which is known as a polymer host for solid polymer electrolytes, especially known for its high lithium ion mobility) and a salt (see e.g. US 5,900,327 B1 or WO 2015/147340 A1). However, the preparation of homogeneous blends is often difficult and phase separation may be observed. WO 2012/095629 A1 addresses this problem by modifying the fluorene-based conjugated polymers so as to reduce the operating voltage of organic electroluminescent devices without necessarily requiring blending with solid polymer electrolytes. The successful implementation of a fluorene-based conjugated polymer in a charge storage device is, however, not reported in these publications.

[0008] Therefore, it remains desirable to provide thin-film charge storage devices which may be manufactured easily and provide for excellent battery performance, as this problem has not been satisfactorily addressed by the prior ait In addition, it would be desirable to provide a simpler method of enhancing the ingress of ions into a bulk of an electroactive polymer.

SUMMARY OF THE INVENTION

[0009] The present invention solves these objects with the subject matter of the claims as defined herein. The advantages of the present invention will be further explained in detail in the section below and further advantages will become apparent to the skilled artisan upon consideration of the invention disclosure.

[0010] In general, the present invention relates to a thin-film charge storage device comprising an electroactive polymer having one or more repeat units, wherein at least one of the repeat units comprises one or more pendant oligo- or polyether groups, which are used to help diffusion of mobile ions from an ionic liquid into the active material consisting of a polymer film and hence enable excellent battery performance. Moreover, as it Is the intrinsic property of the active material polymer to allow for enhanced ionic mobility, the preparation of the active layer does not necessitate blending with polymer electrolytes and salts so that phase separation problems are not observed and the manufacturing Is comparatively simple. Thus, in another aspect, the present invention relates to a method of enhancing migration of ions into a bulk of an electroactive polymer having one or more repeat units, wherein the method comprises modifying at least one of the repeat units with one or more pendant oligo- or polyether groups.

[0011] Preferred embodiments of the charge device and the method according to the present invention and other aspects of the present invention are described in the following description and the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

[0012] FIG. 1 shows a side-sectional view of an exemplary thin-film charge storage device.

[00 3] FIG. 2 shows cyclic voltammograms of stack devices comprising ITO films coated with different polymers and using Pt as counter electrode.

[0014] FIG. 3a is a graph showing the voltage output of battery devices according to the present invention in comparison with devices using F8BT and F8TFB as electroactive polymers.

[0015] FIG. 3b shows the capacitance of battery devices according to the present invention in comparison with devices using F8BT and F8TFB as electroactive polymers.

[0016] FIG. 4a shows the charge discharge curve of a device using F8BT and F8TFB as electroactive polymers.

[0017] FIG. 4b shows the charge discharge curve of a device according to the present invention.

[0018] FIG. 5a is a graph showing the voltage output of a battery device using F8BT and F8TFB as electroactive polymers.

[0019] FIG. 5b shows the capacitance of a battery device using F8BT and F8TFB as electroactive polymers.

[0020] FIG. 6 shows the charge discharge curve of a device using F8BT and F8TFB as electroactive polymers.

DETAILED DESCRIPTION OF THE INVENTION

[0021] For a more complete understanding of the present invention, reference is now made to the following description of the illustrative embodiments thereof: [0022] In one embodiment, the present invention relates to a thin-film charge storage device comprising an electroactive polymer having one or more repeat units, wherein at least one of the repeat units comprises one or more pendant oligo- or polyether groups.

[0023] The term "electroactive polymer", as used herein, denotes a polymer which 5 exhibits variable physical and/or chemical properties resulting from an electrochemical reaction within the polymer upon application of an external electrical potential, and must be thus distinguished from electrochemlcally inert materials or insulating materials, such as conventional electrolytes and porous separator layer supports.

[0024] The electroactive polymer comprising one or more pendant oligo- or polyether groups in a repeat unit thereof may be a p-type or n-type semiconductive polymer.

[0025] If performing as a p-type semiconductive polymer, the electroactive polymer may be selected from known electron donating conjugated organic polymers, provided that it comprises at least one repeating unit having one or more pendant oligo- or polyether groups.

[0026] Preferably, the p-type conjugated organic polymer has a HOMO level between -4.5 and -6.5 eV, more preferably between -4.8 and -6 eV. While deeper HOMO levels may result in a higher battery voltage, the reactivity of the polymer increases, which is accompanied by a lower stability. The HOMO level may be measured by square wave voltammetry. A detailed description of the method will be given below.

[0027] In a preferred embodiment, the p-type conjugated organic polymer is a homopolymer or a co-polymer Including alternating, random or block copolymers. As exemplary p-type conjugated organic polymers, polymers selected from conjugated hydrocarbon or heterocyclic polymers may be mentioned. As examples, in-chain conjugated polymers or co-polymers comprising as monomer units one or more selected from the group consisting of acene, aniline, azulene, benzofuran, fluorene, furan, indenofluorene, indole, phenylene, pyrazoiine, pyrene, pyridazine, pyridine, diarylalkylamine, trlarylamine, phenylene vinylene, 3-substjtuted thiophene, 3,4- bisubstituted thiophene, selenophene, 3-substjtuted selenophene, 3,4-bisubst tuted selenophene, bisthiophene, terthiophene, bisselenophene, terselenophene, thieno[2,3- b]thiophene, thieno[3,2-b]thiophene, benzothiophene, benzo[1 ^-btf.S-bldithiophene, isothianaphthene, monosubstituted pyrrole, 3,4-bisubstituted pyrrole, 1 ,3,4-oxadiazoles, isothianaphthene, and derivatives thereof may be mentioned, provided that at least one monomer unit comprises one or more pendant oligo- or polyether groups as substituent(s). Preferred examples of such p-type polymers are in-chain conjugated homopolymers or co-polymers of monomers selected from at least one, more preferably at least two of the group of fluorenyi derivatives, phenylene derivatives, aniline derivatives, dialkylarylamines, drarylalkylamines, diaryiamines, trlarylamines and heteroaromatic hydrocarbons, wherein at least one monomer unit comprises one or more pendant ollgo- or polyether groups as substituent(s).

[0028] If performing as an n-type semiconductive polymer, the electroactive polymer may be selected from known electron accepting conjugated organic polymers, provided that it comprises at least one repeating unit having one or more pendant oligo- or polyether groups.

[0029] Preferably, the n-type conjugated organic polymer has a LUMO level between -4.5 and -1.5 eV, more preferably between -3.5 and -2 eV. While shallower LUMO levels may result in a higher battery voltage, the reactivity of the polymer increases, which is accompanied by a lower stability. The LUMO level may be measured by square wave voltammetry. A detailed description of the method will be given below.

[0030] Preferably, the n-type conjugated organic polymer is a homopolymer or co-polymer including alternating, random or block copolymers. As exemplary p-type conjugated organic polymers, in-chain conjugated polymers or co-polymers of monomers selected from the group of fluorenyl derivatives, heteroaromatic hydrocarbons (such as e.g. benzothiadiazoles and its derivatives, triazine derivatives (e.g. 1 ,3,5-trtazine derivatives), azafluorene derivatives, or quinoxalines), conjugated aromatic hydrocarbons (e.g. arenes, acenes), carbonyl-based monomers (such as fluorenone derivatives), and derivatives may be mentioned, wherein at least one monomer unit comprises one or more pendant oligo- or polyether groups as substituent(s).

[0031] It will be understood that if the electroactive polymer comprising one or more pendant oligo- or polyether groups in at least one of its repeat units functions an n-type semiconductive polymer, a corresponding p-type semiconductive material is not limited to the above materials and may be suitably chosen from any conventional p-type semiconductive materials known in the art, and vice versa.

[0032] In a generally preferred embodiment, the at least one repeat unit comprising one or more pendant oligo- or polyether groups as substttuent(s) is selected from at least one of the group of fluorenyl derivatives, conjugated aromatic hydrocarbons (e.g. napthalene, phenanthrene, and derivatives thereof), acenaphtene, carbonyl-based monomers, phenylene, anilines (including N-substituted anilines, for example), dialkylarylamines, diary!alkyiamines, diaryiamines (including N-substituted diaryiamines, for example), triarylamines, naphthalene, acenaphtene, phenanthrene, naphthalene dlimide, peryiene diimide, phtalimide, thieno pyrrole dione, heteroaromatic hydrocarbons (e.g. pyridines, quinolines, thiophenes, dithienes, benzothiophenes, benzothiadiazoles, benzotriazoles, carbazoles, and their derivatives), and derivatives thereof. Further preferably, the heteroaromatic hydrocarbons are selected from pyridines, quinolines, thiophenes, dithienes, benzothiophenes, benzothiadiazoles, benzotriazoles, carbazoles, and derivatives thereof. Especially preferably, the at least one repeat unit is selected from at least one of the group of fluorene, dialkylarylamines, diarylalkylamines, diarylamlnes, triarylamines, benzothiadiazole, carbazoles and derivatives thereof.

[0033] it Is further preferred that the efectroactive polymer comprises two repeat units selected from at least one of the group of fluorenyl derivatives, conjugated aromatic hydrocarbons, carbonyl-based monomers, phenylene derivatives, aniline derivatives, dialkylarylamines, diarylalkylamines, diarylamines, triarylamines, heteroaromatic hydrocarbons and their derivatives, wherein the heteroaromatic hydrocarbons are further preferably selected from thiophene, dithiene, benzothiophene, benzothiadiazole, carbazoie and derivatives thereof. Especially preferably, the electroactive polymer comprises two repeat units selected from at least one of the group of fluorene, dialkylarylamines, diarylalkylamines, diarylamines, triarylamines, benzothiadiazole, and derivatives thereof. Here, either one of the repeat units or both may comprise one or more pendant oligo- or polyether groups. When combining two of the above-defined repeating units, the ratio of the two repeating units within the polymer (with respect to the number of units) Is preferably between 90:10 and 10:90, more preferably between 80:20 to 20:80, especially preferably between 30:70 to 70:30.

[0034] In a preferred embodiment of the present invention, the electroactive polymer comprises at least one repeat unit selected from any of the following General Formulae (G-1) to (G-4) described below further preferably at least one repeat unit selected from any of the General Formulae (G-1), (G-3) and (G-4).

[0035]

[0036] In General Formula (G-1), Ri to F¾ are independently selected from hydrogen, optionally substituted Ci.aralkyl, optionally substituted Ci-ao-aIkyl ether, optionally substituted O-arcarboxyl, optionally substituted O-ao-carbonyl, optionally substituted C1-20- ester, optionally substituted Ce-i8-aryl, optionally substituted C eteroaryi groups, and oligo- or polyether groups having at least two alkoxy repeat units, wherein at least one of Ri to Re is an oligo- or polyether group having at least two alkoxy repeat units, and wherein Zi and ¼ are independently selected from a single bond, an optionally substituted Cvaraikyiene, optionally substituted Ci-zo-oxyalkyiene, optionally substituted Cft-iB-arylene, or an optionally substituted Ce-m-heteroarylene group.

[0037] Preferably, at least two of Ri to Re, more preferably at least Ri and R₂ represent an oligo- or polyether group having at least two alkoxy repeat units, which may be identical or different In another preferred embodiment, the residues Ri to Ra which do not represent oligo- or polyether groups having at least two alkoxy repeat units are independently selected from hydrogen, optionally substituted C ₂ alkyl, optionally substituted Ci-₁₂-alkyl ether, optionally substituted Ci-12-carboxyl, optionally substituted Ci.i2-carbonyl, optionally substituted Ci-12-ester, optionally substituted Ce-iz-aryl, optionally substituted Cs-12- heteroaryl groups. In another embodiment, Zi and Z2 may be independently selected from a single bond, an optionally substituted Ci-i2-alkylene, optionally substituted C₁-₁₂- oxyalkylene, optionally substituted Ce-i2-arylene, or an optionally substituted Ce-12- heteroarylene group. More preferably, Zi and Z2 are independently selected from a single bond, a Ci-12-alkylene, and a Ce-i2-arylene group, and further preferably represent optionally substituted phenylenes group, with the residues Ri and R2 preferably representing an oligo- or polyether group having at least two alkoxy repeat units and being preferably located in m- or p-position relative to the fluorene scaffold.

[0038]

[0039] In General Formula (G-2), Re and R10 are independently selected from hydrogen, optionally substituted C_1-20-alkyl, optionally substituted Ci-₂0-alkyl ether, optionally substituted C_1-20-carboxyl, optionally substituted C_1-20-carbonyl, optionally substituted C1-20- ester, optionally substitutedC_6-18 -aryl, optionally substituted Ce-m-heteroaryl groups, and oligo- or polyether groups having at least two alkoxy repeat units, wherein at least one of Rg or Rio is an oligo- or polyether group having at least two alkoxy repeat units, in a preferred embodiment, Rg and R₁0 are independently selected from hydrogen, optionally substituted Ci-i2-alkyl, optionally substituted Ci-12-alkyl ether, optionally substituted C1-12- carboxyl, optionally substituted Ci-i2-carbonyl, optionally substituted Ci-12-ester, optionally substituted Ce.i₂-aryl, optionally substituted Ce-irheteroaryl groups, and oligo- or polyether groups having at least two alkoxy repeat units, wherein at least one of Re or Rio is an oligo- or polyether group having at least two alkoxy repeat units.

[0040]

[0042] In the above General Formulae (G-3) and (G-4), Rn to Rig are independently selected from hydrogen, optionally substituted C_1-20--alkyl, optionally substituted Ci-ao-alkyl ether, optionally substituted d-arcarboxyt, optionally substituted Ci-a>-carbonyl, optionally substituted C_1-20-ester, optionally substitutedC_6-18 -aryl, optionally substitutedC_6-18 - heteroaryl groups, and oligo- or polyether groups having at least two alkoxy repeat units, wherein at least one of R₁₁ to R₁₉, preferably at least Rn, is an oligo- or polyether group having at least two alkoxy repeat units. Index n is greater than or equal to 1 and preferably 1 or 2. Z₃ is selected from a single bond, an optionally substituted C_1-20-aJkylene, optionally substituted C_1-20-oxyalkylene, optionally substituted C_6-18-arylene, or an optionally substitutedC_6-18 -heteroarylene group. In preferred embodiments, R₁₁ to Rig are independently selected from hydrogen, optionally substituted Ci-i2-alkyl, optionally substituted C_1-12-alkyl ether, optionally substituted C_1-12-carboxyl, optionally substituted Ci- 12-carbonyl, optionally substituted Ci-urester, optionally substituted C_6-12-aryl, optionally substituted C_6-12heteroaryl groups, and oligo- or polyether groups having at least two alkoxy repeat units, wherein at least one of R₁₁ to R₁₉ is an oligo- or polyether group having at least two alkoxy repeat units. Index n is greater than or equal to 1 and preferably 1 or 2. 2-3 is selected from a single bond, an optionally substituted C_1-12alkylene, optionally substituted C_1-12-oxyalkylene, optionally substituted Ce-irarylene, or an optionally substituted C_6-12-heteroarylene group. In one embodiment, ¾ is an optionally substituted phenylene group, with the residue Rn being preferably an oligo- or polyether group having at least two alkoxy repeat units and being located in m- or p-position relative to the arylamino group.

[0043] In case the above-defined residues Ri to RIB and Zi to ¾ in General Formulae (G- 1) to (G-4) comprise substituents, it is preferred that the substituents are independently selected from any of the group of halogens, Ci-iralkyl groups, C-w-cycloalkyl groups, Ci- i2-alkoxy groups, Ci-i2-ester groups, amino groups, amido groups, silyl groups, cyano groups or Ci.i₂alkenyl groups.

[0044] In one embodiment, the electroactive polymer may comprise two or more repeating units selected from any of the General Formulae (G-1 ) to (G-4).

[0045] In a particularly preferred embodiment, the electroactive polymer comprises one repeating unit selected from any of the General Formulae (G-1) to (G-4) and one repeating unit which falls into the definition of any of the General Formulae (G-1) to (G-4) except that it does not contain the oligo- or polyether group having at least two alkoxy repeat units. As specific examples thereof, a combination of a repeating unit according to General Formula (G-1) and a repeating unit falling into the definition of any of General Formulae (G-2) to (G-4) - with the exception that It does not contain the oligo- or polyether group having at least two alkoxy repeat units - may be mentioned.

[0046] In general, it may be preferable that the electroactive polymer comprises two different repeating units. While not being limited thereto, the ratio of the two repeating units within the polymer (with respect to the number of units) may be preferably between 90:10 and 10:90, more preferably between 80:20 to 20:80, especially preferably between 30:70 to 70:30.

[0047] The oligoether group, as defined herein, denotes a residue comprising between 2 and 10 oxyaikylene units, each of which may be the same or different, while a polyether group, as defined herein, denotes a residue comprising more than 10 oxyaikylene units, each of which may be the same or different In a preferred embodiment, the oxyaikylene unit comprised in the oligo- or polyether group is an oxyethylene unit

[0048] Preferably, the oligo- or polyether group is represented by one of the following General Formulae (G-5) or (G-6):

wherein Z is selected from a single bond, oxygen, a Ci_-ao-alkylene group, or aC_1-20 - oxyalkylene group; wherein Rao is selected from hydrogen, a hydroxy group, a Cva-alkyl group, a Cva-ester group, or a C_1-20-alkoxy group; and wherein n is at least 2, preferably between 2 and 20, preferably between 2 and 0, more preferably between 2 and 5, 5 especially preferably 3. In a further preferred embodiment, in the oligo- or polyether group represented by one of the following General Formulae (G-5) or (G-6) Z4 is selected from a single bond or oxygen, and/or R20 is selected from hydrogen, a methyl group or an ethyl group.

[0049] The electroactive polymer may be synthesized by methods known in the art, typically by derivatizing the monomers to introduce polymerization-enabling leaving groups (which may include but are not limited to halogens (e.g. bromine), tosylate, mesylate, trfflate, or boronic ester groups) and polymerizing the monomers, e.g. via Suzuki or Yamamoto polymerization (in analogy to WO 00/53656 A1, US 5,777,070 B1, WO 2015/ 47340 A1 , US 5,900,327 B1 , WO 2012/095629 A1 , for example).

[0050] Advantageously, the above-defined polymers exhibit remarkably enhanced electrochemical activity, improve the ionic mobility even inside dense films and allow better ingress of ions resulting in higher battery performances. Hence, thin-film charge storage devices with excellent performance may be manufactured in a simple manner without requiring a modification in the morphology of the active material layer or the formation of blends with further materials (such as e.g. polymer electrolytes and salts).

[0051] The electroactive polymer as used in the present invention may generally further comprise cross-linking units, i.e. functional groups which enable to bond the polymer chains, which may be appropriately chosen by the skilled artisan.

[0052] In addition, the electroactive polymer layers may comprise further additives, such as e.g. plasticizers, surfactants, cross-linking agents or low-molecular weight compounds.

[0053] While not being limited thereto, an exemplary configuration of a thin-film charge storage device is shown in Fig. 1, the device comprising an n-type electroactive polymer layer (2), a p-type electroactive polymer layer (4) and a separator (3) between the electroactive polymer layers, wherein the electroactive polymer having one or more repeat units, of which at least one comprises one or more pendant oligo- or polyether groups, is comprised in or constitutes either one or both of the n-type electroactive polymer layer (2) and tiie p-type electroactive polymer layer (2).

[0054] The thickness of each of the n-type and p-type electroactive layers containing the continuous, solid and porous electroactive polymer material may be chosen appropriately depending on the required purpose and is typically in a range of between 0.05 to 500 pm. For example, layers with relatively low thicknesses may be preferable for applications where high power delivery during a short period of time intervale is required, whereas relatively thick layers may be preferable for uses requiring higher charge contents.

[0055] Typically, as in the configuration of Fig. 1 , the charge storage device comprises current collector layers (1) and (5) at the side of the polymer layers opposed to the separator. Suitable materials for current collector layers include material that is selected from the group consisting of porous graphite, porous, highly doped inorganic semiconductor, highly doped conjugated polymer, carbon nanotubes or carbon particles dispersed In a non-conjugated polymer matrix, aluminum, silver, platinum, gold, palladium, tungsten, indium, zinc, copper, nickel, iron, stainless steel, lead, lead oxide, tin oxide, indium tin oxide, graphite, doped silicon, doped germanium, doped gallium arsenide, doped polyaniline, doped polypyrrole, doped poiythiophene, and their derivatives, with indium tin oxide being particularly preferred.

[0056] While the electroactive polymer layers may consist of the electroactive polymers, the layers may comprise further materials that are conventionally used in the preparation of polymeric films for charge storage devices. For example, electroactive polymer layers may be combined with one or more layers that may be polymeric or non-polymeric and/or comprise material embedded into the respective polymer films (e.g. a conductive material for electrode connection etc.). Also, instead of using separate current collector layers (1) and (5), conductive particles (such as carbon nanotubes or carbon particles, for example) may be dispersed in the polymer layers (2) and (4) at a concentration higher than a percolation threshold concentration in order for the polymer layers to perform as current collectors. In addition to the above, a substrate layer may be provided adjacent to the electroactive polymer layers, e.g. as a mechanical support.

[0057] The material for the separator layer (3) Is not particularly limited and may be made of known materials that are chemically and electrochemically unreactive with respect to the charges and to the electrode polymer materials in their neutral and charged states.

[0058] Typically, the separator contacts the n-type and p-type electroactive polymer layers (2) and (4) such that the transport of ions is facilitated. As suitable materials, porous polymeric materials (e.g. polyethylene, polypropylene, polyester, teflon or cellulose-based polymers), ion-conductive polymer membranes (e.g. Nation™), (electronically nonconductive) gel electrolytes (e.g. polymers, copolymers and oligomers having monomer units selected from the group consisting of substituted or unsubstituted vinylidene fluoride, urethane, ethylene oxide, propylene oxide, acrylonitrile, methylmethacrylate, alkylacrylate, acrylamide, vinyl acetate, vinylpyrrolidinone, tetraethylene glycol diacrylate, phosphazene and dimethylsiloxane), cellulose-based gel electrolytes or cellulose-based membranes (e.g. filter paper) may be mentioned, with the proviso that the materials are resistant towards dissolution by the electrolyte, which may be appropriately achieved by methods known to the skilled artisan (e.g. by suitable selection of materials or by cross-linking in case of polymers).

[0059] The separator layer thickness may likewise be appropriately selected by the skilled artisan depending on the purpose. Typically, the separator thickness is between 5 prn and 100 pm.

[0060] The electrolyte for use in the charge storage device of the present invention is not particularly limited and may be suitably selected by the skilled artisan depending on the chosen separator and electroactive materials. As examples thereof, electrolyte salts dissolved in appropriate solvents as commonly used in the art or ionic liquids that are typically liquid below 100 °C may be mentioned, the latter including, but not being limited to ammonium-, imidazolium-, phosphonium-, pyridinium-, pyrrolidinium-, and suifonium- based ionic liquids. Other preferred examples include bis(trif)uoromethane)sutfonimide (TFSI)-based ionic liquids such as e.g. 1-ethyi-3-methyl imidazolium bis(trifluoromethane)sulfonimide (EMI-TFSI), triethylmethoxyethyl phosphonium bis(trifluoromethane)suifonimide (TEMEP-TFSI), triethyl sutfonium bis(trifluoromethane)sulfonimide (TES-TFSI) or 1-butyM-methylpyrrolidinium bis(trifluoromethane)sulfonimide (BMP-TSFI), the latter being particularly preferable.

[0061] It is to be understood that the charge storage device according to the present invention may also comprise additional layers not shown in Fig. 1, such as one or more encapsulation layers, for example.

[0062] In a preferred embodiment, the charge storage device of the present invention is a thin-film charge storage device and/or a battery and/or a battery/supercapacitor hybrid. More preferably, the charge storage device of the present invention is a polymer battery.

[0063] The layer comprising the electroactive polymer may exhibit a morphology which additionally enhances the movement of ions, such as a continuous, solid and porous structure which may be achieved by providing the electroactive polymer layer as an aggregate of electroactive polymer particles or fibers (i.e. nano and/or microfibers); as an open-cell foam; as a gel; and/or by providing the layer with a non-planar surface. However, taking into account the favourable ion-transporting properties of the electroactive polymer comprising the at least one repeat unit having one or more pendant oligo- or polyether groups and in view of the simplicity of the manufacturing method, it may be preferable to provide the layer comprising the electroactive polymer as a neat film.

[0064] The charge storage device according to the present invention may be manufactured by conventional processes known in the art. For example, the electroactive polymer layer may be fabricated by a solution deposition or coating process, which is often followed by a heating treatment in order to further enhance the densification and uniformity of the layer. The method of film deposition may include thermal deposition, vacuum deposition, laser deposition, screen printing, printing, imprinting, spin coating, dipping, inkjetting, roll coating, flow coating, drop casting, spray coating, and/or roll printing, for example. Alternatively, the layer comprising the electroactive polymer (e.g. the n-type and/or p-type electroactive polymer layer) may be manufactured by polymerizing one (or more) monomer(s) of the desired conjugated by electropolymerization or chemical polymerization.

[0065] In a further embodiment, the present invention relates to a method of enhancing migration of ions into a bulk of an electroactive polymer having one or more repeat units, wherein the method comprises modifying at least one of the repeat units with one or more pendant oligo- or polyether groups. By using the pendant oligo- or polyether groups as polymer substituents, the ingress of ions is facilitated and the electrochemical activity and ionic mobility of the electroactive polymer is improved. The methods of synthesizing and/or substituting the modified electroactive polymers with one or more pendant oligo- or polyether groups are not particularly limited and may be appropriately selected by the skilled artisan from methods known in the art.

[0066] In a preferred embodiment of the method, the electroactive polymer may be comprised In a charge storage device, further preferably a thin-film charge storage device.

[0067] While not being limited thereto, the electroactive polymer forming the bulk may be defined in accordance with the electroactive polymer described above in the context of the charge storage device.

[0068] In general, it will be appreciated that the preferred features specified above may be combined in any combination, except for combinations where at least some of the features are mutually exclusive.

EXAMPLES

[0069] In an initial series of experiments, the electrochemical activity of ITO electrodes with different polymer coatings has been evaluated. An overview of the polymers used in the examples and the structures thereof are given in Table 1 and the following structural formulae:

[0070] TABLE 1

Example 1

[0072] In Example 1, Polymer A (Mw = 29000; „ = 13000), a polymer comprising repeating units with pendant oligoether groups, has been synthesized from a dibromide of monomer (A-1) and a boronlc acid diester of monomer (M)

[0073] Polymer A exhibits a HOMO level of -6.05 eV and a LUMO level -3.01 eV, which has been determined via square wave voltammetry using a CHI660D Electrochemical workstation with software (I J Cambria Scientific lid)), a CH1 104 3mm glassy carbon disk working electrode (IJ Cambria Scientific Ltd)); a platinum wire auxiliary electrode; an Ag/AgCI reference electrode (Havard Apparatus Ltd); acetonitrile as cell solution solvent (Hi-dry anhydrous grade-ROMIL); toluene as sample preparation solvent (Hi-dry anhydrous grade); ferrocene as reference standard (FLUKA); and tetrabutylammonlumhexafluorophosphate (FLUKA) as cell solution salt. For sample preparation, the polymer was spun as thin film (-20 nm) onto the working electrode and the dopant material was measured as a dilute solution (0.3 w%) in toluene. The measurement cell contained the electrolyte, a glassy carbon working electrode onto which the sample was coated as a thin film, a platinum counter electrode, and a Ag/AgCI reference glass electrode. Ferrocene was added into the cell at the end of the experiment as reference material (LUMO (ferrocene) = -4.8eV).

[0074] Thereafter, Polymer A was spin-coated on an ΓΤΟ layer having a thickness of 100 nm. CV scans at a scan rate of 100 mV/s have been performed using 1M tetrabutylammonlum hexafluorophosphate (TBAPF₆) in acetonrtrile as electrolyte, the n- type polymer-coated ITO as working electrode, Pt as counter electrode, and Ag/AgCI as reference electrode.

Comparative -Example 1

[0075] In a comparative example, a polymer-coated ITO electrode has been prepared in accordance with Example 1 , with the exception that poly(9,9-dioctyffluorene-a/f- benzothiadiazoie) (F8BT), a commercially available fluorene derivative having the chemical formula shown above has been used as a polymer.

[0076] The results of the cyclic voltammetry measurements are shown In Fig. 2. The graphs in Fig. 2 demonstrate that no redox current is observed for the F8BT-coated ITO, whereas the sample comprising Polymer A shows clear reversible reduction current. Moreover, it is shown that Polymer A is electrochemically active on ITO with similar reduction potential of approximately -1.45 V and currents of same magnitude (deviations caused by different electrode areas). Thus, it has been confirmed that films of F8BT even when used in layers as thin as 00 nm on ITO are inactive whilst films of Polymer A on ITO enable excellent performance as an active material in a battery setup.

Example 2

[0077] In a further example, a thin-film battery having a device architecture in accordance to Fig. 1 with the following configuration has been manufactured:

[0078] For this purpose, Polymer A was spin-coated from a 2.5 wt.-%-solution in anisole onto ITO bottom contacts on glass in air to form an n-type polymer layer having a thickness of 100 nm, and F8TFB (see formula below) was spin-coated from a 1 wt.-%- solution in toluene on a second ITO/glass layer to form a p-type polymer layer having a thickness of 100 nm:

[0079] Thereafter, PM A/BMP-TFSI (1:4 w/w) was drop-casted from a 10 wL-%-solutlon in 2-butanone on top of each of the n-type and p-type polymer layers In a glove box and dried at 120°C for 20 min. After drying, the plates with the n-type material and the p-type material were sandwiched and kept overnight in the glove box.

Comparative Example 2

[0080] Comparative Example 2 has been prepared in accordance with Example 2, with the exception that the n-type polymer layer has been prepared by spin-coating F8BT from a 2 wt.-%-solution in toluene instead of using Polymer A.

Comparative Example 3

[0081] In Comparative Example 3, a device architecture has been tested which employs filter paper as the separator material:

[0082] Initially, two ITO/glass plates were spin-coated F8BT from a 2 wL-%-solution in toluene to provide the n-type polymer layer and with F8TFB in accordance with Example 2 to provide the n-type polymer layer. The filter paper was dried in a vacuum oven, soaked in ionic liquid B P-TFSI and provided between the coated ITO/glass plates. The construction was sandwiched by means of two metal clips.

[0083] The devices of Example 2 and Comparative Examples 2 and 3 were then tested. Clips, if present, were removed and the devices were placed into a sealed glass container and connected to a potentiostat (CHI660D Electrochemical Workstation by CH Instruments inc., with software (IJ Cambria Scientific Ltd.)). The measurement conditions were as follows:

[0084] The cycle-dependent voltage and capacitance data and the charge-discharge curves obtained for the devices of [Example 2 and Comparative Example 2 are shown in Figures 3a, 3b, 4a and 4b. In contrast to Comparative Example 2, which displays capacltfve-like behavior with voltages below 1.2 V and a capacitance of less than 0.00018 mAh/cm², the device of Example 2 displays clear battery behavior with a well-defined faradaic discharge plateau with a voltage of over 2.1 V. The energy content (in mWh/cm²) of the device of Example 2 has been measured to be 47 times higher than that of Comparative Example 2.

[0085] As shown in Figures 5a, 5b, 6a and 6b, Comparative Example 3 displays capacitJve-like behavior, similar to Comparative Example 2, with voltages below 0.5 V and a capacitance of less than 0.0004 mAh/cm².

[0086] The measurement results summarized in Table 2 demonstrate that the use of a polymer having one or more repeat units, wherein at least one of the repeat units comprises one or more pendant oligo- or polyether groups provides for excellent electrochemical activity and enables production of charge storage devices which exhibit excellent performance:

[0087] TABLE 2

[0088] Once given the above disclosure, many other features, modifications, and improvements will become apparent to the skilled artisan. REFERENCE NUMERALS

1 : first current collector layer

2: n-type electroactive polymer layer

3: separator

4: p-type electroactive polymer layer 5: second current collector layer

Claims

1. A charge storage device comprising either one electroactive polymer that can be both p-doped and n-doped, or two separate polymers of which one can be p-doped and the other n-doped, said polymer(s) having one or more repeat units, wherein at least one of the repeat units comprises one or more pendant oligo- or polyether groups.

2. The charge storage device according to claim , wherein the at least one repeat unit having one or more pendant oligo- or polyether groups as substituent(s) is selected from at least one of the group of fluorenyl derivatives, conjugated aromatic hydrocarbons, acenaphtene, carbonyl-based monomers, phenylene, aniline, dialkylarylamines, diarylaikylamines, diarylamines, triarylamines, naphthalene, acenaphtene, phenanthrene, naphthalene diimide, perylene diimide, phtalimide, thieno pyrrole dione, heteroaromatic hydrocarbons, and derivatives thereof; wherein the heteroaromatic hydrocarbons are preferably selected from pyridines, quinolines, thiophenes, dithienes, benzothiophenes, benzothiadiazoles, benzotriazoles, carbazoles, and derivatives thereof.

3. The charge storage device according to claim 1 , wherein the at least one repeat unit having one or more pendant oligo- or polyether groups as substituent(s) is selected from at least one of the group of fluorenyl derivatives, conjugated aromatic hydrocarbons, acenaphtene, carbonyl-based monomers, phenylene, aniline, dialkylarylamines, diarylaikylamines, diarylamines, triarylamines, naphthalene, acenaphtene, phenanthrene, naphthalene diimide, perylene diimide, phtalimide, thieno pyrrole dione, heteroaromatic hydrocarbons, and derivatives thereof; wherein the heteroaromatic hydrocarbons are preferably selected from pyridines, quinolines, thiazoles, dithienes, benzothiophenes, benzothiadiazoles, benzotriazoles, carbazoles, and derivatives thereof.

4. The charge storage device according to any of claims 1 to 3, wherein the at least one repeat unit having one or more pendant oligo- or polyether groups as substituent(s) is selected from at least one of the group of fluorenes, dialkylarylamines, diarylaikylamines, diarylamines, triarylamines, benzothiadiazole, carbazoles and derivatives thereof.

5. The charge storage device according to any of claims 1 to 4, wherein the electroactive polymer comprises two repeat units selected from the group of fluorene, dialkylarylamines, diarylaikylamines, diarylamines, triarylamines, benzothiadiazole, and derivatives thereof, wherein at feast one of the repeat units comprises one or more pendant oligo- or polyether groups as substituent(s), and wherein the ratio of the two repeating units within the polymer is preferably between 30:70 to 70:30.

6. The charge storage device according to any of claims 1 to 5, wherein the electroactive polymer comprises at least one repeat unit selected from any of the following General Formulae (G-1) to (G-4):

wherein Ri to Re are independently selected from hydrogen, optionally substituted C_1-20-alkyl, optionally substituted C_1-20-alkyl ether, optionally substituted C_1--₂a₀rcarboxyl, optionally substituted C_1-20-est.er, optionally substituted C_1-20-carbonyl, optionally substituted C_8-18-aryl, optionally substituted C_6-18heteroaryl groups, and oligo- or polyether groups having at least two alkoxy repeat units,

wherein at least one of R₁ to R₈ is an oligo- or polyether group having at least two alkoxy repeat units, and

wherein Z₁ and Z₂ are independently selected from a single bond, an optionally substituted Ci-araJkylene, optionally substituted C_1-20-oxyalkylene, optionally substituted Ce-ia-arylene, or an optionally substituted C_6-18-heteroarylene group;

wherein R₉ and R₁₀ are independently selected from hydrogen, optionally substituted C_1-20-alkyl, optionally substituted C_1-20 alkyl ether, optionally substituted C_1-20 - carboxyl, optionally substituted C_1-20-ester, optionally substituted Ci-ao-carbonyl, optionally substituted C_8-18-aryl optionally substituted C_6-18-heteroaryl groups, and oligo- or polyether groups having at least two alkoxy repeat units, wherein at least one of Re or Rio is an oligo- or polyether group having at least two alkoxy repeat units;

wherein Rn to Ri_B are independently selected from hydrogen, optionally substituted Ci.a>-alkyl, optionally substituted Ci^o-alkyI ether, optionally substituted C₁.₂₀- carboxyl, optionally substituted C_1-20-ester, optionally substituted Ci^o-carbonyl, optionally substitutedC_6-18 -aryl, optionally substitutedC_6-18 -heteroaryl groups, and oligo- or polyether groups having at least two alkoxy repeat units,

wherein at least one of Rn to Rig is an oligo- or polyether group having at least two alkoxy repeat units,

wherein n is greater than or equal to 1 , preferably 1 or 2, and

wherein ¾ is selected from a single bond, an optionally substituted Ci-₂o-aIkylene, optionally substituted Ci-a-oxyalkylene, optionally substituted Ce-urarylene, or an optionally substituted Ce-is-heteroarylene group.

7. The charge storage device according to claim 6, wherein the electroactJve polymer comprises two repeating units selected from any of the General Formulae (G-1) to (G-4), the ratio of the two repeating units within the polymer being preferably between 30:70 to 70:30.

8. The charge storage device according to any of claims 1 to 7, wherein the oligo- or polyether group comprises at least two oxyalkylene units, the oxyalkylene units being preferably oxyethylene units. 9. The charge storage device according to any of claims 1 to 8, wherein the oligo- or polyether group is represented by one of the following General Formulae (G-5) or (G-6):

wherein 2 is selected from a single bond, oxygen, a &.₂o-alkylene group, or a Ci- 20-oxyalkylene group;

wherein R20 is selected from hydrogen, a hydroxy group, a Ci-zo-alkyl group, or a C_1-20-alkoxy group; and

wherein n is at least 2, preferably between 2 and 20, preferably between 2 and 10, more preferably between 2 and 5, especially preferably 3. 10. The charge storage device according to claim 9,

wherein Z» is selected from a single bond or oxygen, and/or

wherein R20 is selected from hydrogen, a methyl group or an ethyl group; and/or wherein n is 3. 11. The charge storage device according to claim 9,

wherein Z» is selected from a single bond or oxygen,

wherein F¾o is a methyl group or an ethyl group, and

wherein n is 3. 12. The charge storage device according to any of claims 1 to 11 comprising an n-type electroactive polymer layer, a p-type electroactive polymer layer and a separator between the electroactive polymer layers, wherein the electroactive polymer having one or more repeat units, of which at least one comprises one or more pendant oligo- or polyether groups, is comprised in either one or both of the n-type electroactive polymer layer and the p-type electroactive polymer layer.

3. The charge storage device according to any of claims 1 to 12, wherein the charge storage device is a polymer battery.

14. The charge storage device according to any of claims 1 to 12, wherein the charge storage device is a thin-film charge storage device.

15. Method of enhancing migration of ions Into a bulk of an electroactive polymer having one or more repeat units, wherein the method comprises modifying at least one of the repeat units with one or more pendant oligo- or polyether groups.

16. Method according to claim 15, wherein the at least one repeat unit having one or more pendant oligo- or polyether groups as substituent(s) is selected from at least one of the group of fluorenyl derivatives, conjugated aromatic hydrocarbons, acenaphtene, carbonyl-based monomers, phenylene, aniline, dialkylarylamines, diarylalkylamines, diarylamines, triarylamines, naphthalene, acenaphtene, phenanthrene, naphthalene dilmfde, peryfene diimide, phtalimide, thieno pyrrole dione, heteroaromatic hydrocarbons, and derivatives thereof; wherein the heteroaromatic hydrocarbons are preferably selected from pyridines, quinolines, thiazoles, dithienes, benzothiophenes, benzothiadiazoles, benzotriazoles, carbazoles, and derivatives thereof.

17. Method according to claim 15, wherein the electroactive polymer is comprised in a charge storage device, preferably a thin-film charge storage device.