CONDUCTING POLYMERS

Abstract

There is described a process for forming a conformal film of conducting polymer onto one or more surfaces of a substrate by polymerising onto the one or more surfaces in a single step one or more conducting polymer precursors including one or more monomers in the presence of conductivity enhancing additives comprising one or more ionic liquids and one or more optional ionic dopants.

Claims

1. (canceled)

2. (canceled)

3. A process for forming a surface bound conformal film of an electrically insulating ion conducting polymer onto one or more surfaces of a substrate wherein the polymer has conductivity enhancing additives entrained therein, the process comprising the step of: forming and surface binding the polymer film by polymerising onto the one or more surfaces in a single step one or more conducting polymer precursors including one or more monomers in the presence of conductivity enhancing additives comprising one or more ionic liquids having a melting point below 100 C., wherein the one or more conducting polymer precursors are present in amounts that provide a substantially pinhole free polymer film having substantially all of the conductivity enhancing additives entrained therein, and wherein on formation on the surface the polymer film is free of non-ionic liquid solvent.

4. The process of claim 3 wherein the conductivity enhancing additives consist of one or more ionic liquids having a melting point below 100 C. or the combination of one or more ionic liquids having a melting point below 100 C. and one or more metal salts.

5. (canceled)

6. The process of claim 3, wherein the conducting polymer precursors and the conductivity enhancing additives are simultaneously present at the surface when formation and surface binding of the polymer onto the surface occurs, and are provided to the surface in the form of a single mixture.

7. The process of claim 3, wherein the polymer film is formed and surface bound to the surface through generation of an initiator radical ion on the surface which propagates polymer chain formation from conducting polymer precursors present at the surface.

8. The process of claim 7, wherein the initiator radical ion is generated at the surface from the one or more conducting polymer precursors, preferably on application of sufficient negative or positive electrical potential to the surface.

9. The process of claim 7, wherein the initiator radical ion is chemisorbed, covalently bound or grafted onto the activated surface on formation and remains so during polymer chain propagation.

10. The process of claim 7, wherein the initiator radical ion is a radical ion formed from a one electron redox process (oxidation or reduction), involving monomer and/or other conducting polymer precursors present at the surface.

11. (canceled)

12. The process of claim 10, whereby generation of the initiator radical ion through a redox process at the surface occurs via electrografting, electropolymerisation or other electro process suitable for forming and surface binding a radical ion to the surface.

13. The process of claim 3, whereby the conductivity enhancing additives further comprise ionic dopants.

14. The process of claim 13, wherein the ionic dopants are one or more metal salts MzXy, preferably where M is selected from the group consisting of Li, Na, K, Be, Mg, Ca, B, Al, and Zn; and where X is a negatively charged ion (anion) selected from the group consisting of: TFSI, FSI, PF.sub.6, BF.sub.4, CF.sub.3SO.sub.3, (Alkyl)BF.sub.3, (Alkyl)nB(CN).sub.4-n, where n is from 0 to 4.

15. The process of claim 3, wherein the ionic liquid:monomer concentration ratio is such that at least 80-90% of the ionic liquid is incorporated/entrained in the polymer.

16. The process of claim 3, wherein the monomer is a diacrylate or monoacrylate monomer, the ionic liquid proportion is up to 40 wt % (based on total amount of monomer and ionic liquid).

17. The process of claim 3, wherein the surface is a polarisable substrate capable of holding a charge when a suitable potential is applied thereto, selected as one from a metal, a metal alloy, a semi-conductor, an electrode or a material typically used in energy storage devices including batteries and capacitors, and an electronically conducting polymer.

18. (canceled)

19. The process of claim 3, wherein the substantially pinhole free film is one having a substantially uniform thickness not deviating from film mean thickness by more than 10%.

20. (canceled)

21. The process of claim 3, wherein in addition to the one or more monomers, the one or more of the conductivity enhancing additives comprise at least one polymerisable functional group and/or one or more hydrophilic, hydrophobic, or other reactive groups, pH responsive groups, emissive, absorptive, and/or fluorescent groups, wherein the polymerisable functional group is selected from the group consisting of acrylate, vinyl, styrene, acrylonitrile, olefin and/or other polymerisable groups which may be optionally substituted with groups such as alkyl groups, or one or more ionisable or cross linkable functional groups such as COOH or NH.sub.2.

22. (canceled)

23. (canceled)

24. A precursor mixture for forming a conformal film of an electrically insulating ion conducting polymer onto one or more surfaces of a substrate in a single electrosynthetic step, the mixture consisting essentially of one or more monomers, one or more ionic liquids having a melting point of less than 100 C., and optionally one or more metal salts, wherein the relative amounts of the one or more conducting polymer precursors is such that on polymerisation substantially all of the ionic liquid and ionic dopant, if present, is incorporated/entrained in the polymer without formation of a miscibility gap, and wherein the one or more conducting polymer precursors are free of non-ionic liquid solvent.

25. A product obtainable by the process of claim 3, preferably having an ionic conductivity of at least 110.sup.5 S/cm at ambient temperature.

26. An energy storage device comprising the product of claim 25 as an electrolyte; and/or separator of a battery ora photovoltaic device.

27. An energy storage device comprising an electrically insulating solid polymer electrolyte surface bound through electrografting as a conformal film of ion conducting polymer onto one or more surfaces of an electrically conductive substrate wherein the polymer has conductivity enhancing additives entrained therein, the conductivity enhancing additives comprising one or more ionic liquids having a melting point below 100 C. and one or more lithium metal salts, wherein the solid polymer electrolyte is substantially pinhole free having substantially all of the conductivity enhancing additives entrained therein.

28. Use of the product of claim 25 in an application selected from a coating application, membrane technology, corrosion or other protecting technologies, a microsensing application, biomedical applications; environmental applications; photovoltaic applications; as a dielectric material in electrochemical capacitors; as modified surfaces for chemical and electrochemical sensors and biosensors; fuel cells and electrolysis membranes; as a modified surfaces in microelectronics and MEMS industry; as a surface modifier for conducting glasses; as a surface modifier without the ionic dopant in general where ionic conduction is not required; in energy storage for microrobotics or for implantable devices; energy harvesting devices and microsupercapacitors, or in methods for applying an ionically conducting polymer to conductive surfaces.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0132] FIGS. 1(a) and 1(b) are SEMs of a conformally coated pillar 3-D substrate after coating with tin (PEO-DA electro-polymerisation at 2.5V for 2 min onto Sn coated micro pillars) and composite polymer; the two sets of images show the difference in surface morphology after different reaction times for polymer coat formation suitable for a battery.; FIG. 1(b) is a close up of an anode surface coated in polymer; FIG. 1(c) is a comparison between a partially coated and uncoated surface.

[0133] FIGS. 2(a) and 2(b) are graphs showing the resistance ionic conductivity of a number of SPEs of the invention against temperature.

[0134] FIG. 3 is a cyclic voltammograms of a ternary PEO-DA/10 wt % P14-TFSI/0.6 molkg.sup.1 LiTFSI precursor mixture. Consecutive scans are depicted: 1.sup.st scan (red), 2.sup.nd scan (purple), 3.sup.rd scan (green), 4.sup.th scan (turquoise) all recorded at =20 mVs.sup.1 on a copper substrate.

[0135] FIG. 4 is a representative charge/discharge profile recorded with a 2D test battery to demonstrate cyclability of the electrolyte: lithium metal (anode), lithium iron phosphate (cathode) assembled in standard coin cell.

[0136] FIG. 5 is a schematic showing a number of exemplary ionic liquid anions of the invention, wherein each R, R, and R.sub.1-R.sub.6 is independently any organic/inorganic group which can be suitably used as part of an ionic liquid anion, but preferably are selected from R.sub.aN(SO.sub.2F), wherein R.sub.a may be optionally substituted aryl, alkyl, alkyl-SO.sub.2, aryl-SO.sub.2, alkyl-CO, aryl-CO, (alkyl).sub.2PO, (aryl).sub.2PO, (alkyl)(aryl)PO, (alkylO).sub.2PO, (arylO).sub.2PO, (alkylO)(arylO)PO; in all cases the optionally substituted alkyl and aryl can optionally be fully or partially fluorinated, the alkyl and aryl groups can be linear or branched; the optionally substituted alkyl and aryl groups can contain ether functionalities; in RNNR anions (in the bottom right of FIG. 3), R may be optionally substituted alkyl, aryl, alkyl and aryl may independent be fully or partially fluorinated, alkyl and aryl groups can be linear or branched; alkyl and aryl groups can contain ether functionalities.

[0137] FIG. 6 is a schematic showing a number of exemplary ionic liquid cations of the invention, wherein R is any organic group which can be suitably used as part of an ionic liquid cation, wherein R may be independently selected from optionally substituted alkyl, aryl, alkyl and aryl, which can optionally be fully or partially fluorinated; optionally substituted alkyl and aryl groups which can be linear or branched; optionally substituted alkyl and aryl groups can contain ether functionalities.

DETAILED DESCRIPTION OF THE INVENTION

[0138] The invention described herein relates to the development of a single-step process to apply an electrically insulating polymer conducting polymer or battery electrolyte, incorporating all necessary conductivity enhancers and lithium-ion dopants, in a thin and conformal coating over a conductive substrate. A preferred intended application is the use of the polymer as a solid polymeric electrolyte (SPE) in 3DMBs. However, the process could also be used in other lithium-ion battery systems which utilise a polymer electrolyte in place of a liquid electrolyte.

[0139] The invention relates to the development of a new process to apply a solid polymer electrolyte, possessing all of the necessary criteria and performance enhancing additives mentioned above, in a single fabrication step. In one preferred embodiment, the fabrication process involves the electrografting of a monomer onto a battery anode surface from a solution comprised of only an ionic liquid, the monomer and a lithium salt.

[0140] The process of electrografting involves the use of a charged electrode to initiate the polymer grafting step (i.e. surface bound deposition), after which point the thickening of the polymer can be controlled by the electrode potential or can occur independently of the electrode potential. Typically, electrografting must occur from a solution that is comprised of a reducible monomer, a solvent and a supporting electrolyte. In prior art methods, acetonitrile (ACN), ethanol (EtOH) and dimethylformamide (DMF) are common solvents that are used due to the fact that they are inert under the electrochemical conditions (i.e. potentials) used to form the polymer, whilst electrochemically inactive salts such as tetraethylammonium perchlorate (TEAP) are used as the supporting electrolyte to provide sufficient conductivity for the electrografting process. In the process relating to the current invention, an ionic liquid is advantageously used as both ion conductivity enhancing additive and as supporting electrolyte in the electrografting process wherein the amount of ionic liquid used is an amount that can be fully incorporated into or entrained within the polymer. By fully incorporated or entrained, it is meant that at least 80-90%, and more preferably 90%-100% of the ionic liquid used becomes entrained within the polymer. Processing advantages include the avoidance of the need for an excess/unreacted IL and/or conventional solvent removal steps.

[0141] The ionic liquid, initially serving as ion conductivity enhancing additive and supporting electrolyte in the electrografting process, subsequently becomes fully incorporated or entrained into the resultant polymer to function as a plasticiser/conductivity enhancer for the SPE as defined above. It will be understood that, when present, the dopant, for example, lithium salt is also incorporated into the SPE as a result of being present in the electrografting solution. Amounts of the one or more dopant are also chosen to ensure that substantially all of the dopant is incorporated into the polymer during the single step fabrication process.

[0142] Some key advantages of the films/coatings of the invention are as follows:

[0143] The process is a simple and convenient one-step process.

[0144] The films/coatings of the invention are conformally fabricated, and are capable of completely covering a 3D surface with a high aspect ratio. An example of such a structure is a pillared array in which the pillars are 10 microns in diameter, 10 microns apart and 100 microns long(see FIG. 1, for example). The films/coatings of the invention are thin and substantially pinhole-free. In other words, the films are several tens of nanometers to one hundred nanometers thick and the diameter of any pores within a film are smaller than the thickness of the film.

[0145] The films/coatings of the invention contain multiple components (polymer, conductive additive and metal salts) that are evenly distributed throughout. By evenly distributed we mean that on the scale of tens of nanometers the electrical properties of the film are isotropic.

[0146] Finally, the surface bound nature of the film/coating of the invention means that the ionically-conducting polymer film is intimate contact with the electronically-conducting surface. Intimate contact means sufficiently close that the barrier to charge transfer from the electronic conductor to the ionic conductor is negligible. Charge transfer at such an interface involves electron tunneling across the interface, so practically, this means the polymer film must be within a few atomic layers of the electronically conducting surface.

EXAMPLES

[0147] Resistance and conductivity results for a number of exemplary films of the invention are provided in Tables 1-6 below.

[0148] Conductivity Data for Exemplary Ternary Polymer Blends were Obtained by the Following Methodology

[0149] In a first step, the respective monomer and ionic liquid were mixed in the required weight % proportions under dry conditions (i.e., in an inert gas filled glove box). To this mixture of known weight was added in a second step, the required amount (mol/kg) of an ionic dopant, i.e., a lithium salt in portions while stirring under dry conditions. In order to facilitate the dissolution process this mixture may be heated to 40-50 C. If required, stirring may be continued for one day at this temperature or room temperature. This mixture may be kept as a stock solution for multiple sample preparation at 4 C. and protected from light for several weeks. In the third step for polymer film formation an aliquot of this solution is brought into contact with 1 wt % of a radical initiator (i.e. AIBN, organic peroxides, etc.) under ultrasonication at room temperature for suspending the initiator in the mixture. The thus formed suspension is then applied to a mould (i.e. Petri dish, silicone mould, etc.) in a volume quantity estimated from the mould diameter to give a polymer film close to that of the target thickness of the film. In a fourth step, polymerisation of the mixture is then initiated by setting the filled mould in a laboratory oven at 30 to 80 C., depending on the nature of the radical initiator and the monomer, preferably near 40 C. if AIBN is used. After resting for 12-24 h at this temperature the cured polymer film is cooled to ambient temperature and kept under vacuum for 12-24 h.

[0150] From the finished polymer circular films of 12-15 mm diameter are cut by means of hole punch and their thickness is measured before being enclosed in standard coin cells used in battery assembly. The coin cell assembly is then placed in a temperature controlled oven and connected to the impedance unit of a potentiostat and data collection is performed by applying an AC current over a frequency range of 10 to 100.000 Hz. Data are first collected during a heating cycle followed by data collection during the cooling down cycle. A rest period of at least 24 h was allowed between each temperature point to allow for sufficient equilibration of the polymer sample. The ohmic resistance for a selected temperature is estimated from the touch-down point of the frequency response on the Z axis (ohmic resistance) of the Nynquist plot generated from the measurement. The conductivity value (a) for the selected temperature is obtained from the equation =L/A1/Z where L is the thickness of the polymer film and A is the area of the film. Typically for each polymer material duplicate cells are constructed and measured. From the collected data, the graph shown in FIG. 2 displaying the temperature dependent conductivity for individual ternary polymer blends was generated.

[0151] Typical Procedure for the Preparation of Polymer Films on Conducting Surfaces, i.e. Battery Electrodes of the Invention

[0152] Because of the moisture sensitivity of the ionic components, this procedure is conducted an inert gas filled glove box.

[0153] A suitable cell equipped with a counter electrode (Pt or stainless steel) and a Pt-wire quasi reference electrode was filled with the target monomer blend prepared according to the procedure of paragraph 1111 above, but without addition of a radical initiator.

[0154] The electrode material (pre dried under vacuum) to be coated was then fitted to the cell and all electrodes were connected to a conventional potentiostat. In a first step, the integrity of the monomer blend and its electrochemical behaviour were confirmed by recording a cyclic voltammogram of the monomer blend at a scan rate of 20 to 100 mV/s. In the second step, the electrochemical method was then switched to applying a constant potential, i.e. -2.5V, as per cyclic voltammogram for a set period of time after which the electrode was removed from the solution and the exposed surface rinsed with a small quantity of methanol. The electrografting of a polymer film onto the surface was verified by recording SEM images of the exposed electrode and comparison with SEM images of the neat material. In addition surface conductivity measurements are performed.

[0155] Additional Information Relating to the Cyclability of the Polymeric Electrolyte in a Lithium Battery

[0156] Under inert conditions, standard coin cells (CR2032 stainless steel cell, Hosen company, Japan) were assembled with lithium iron phosphate (LFP) cathode foil discs (10.5 mm diam.; 75 wt % LFP) and lithium metal foil discs (12 mm diam.) and a pre-fabricated ternary composite polymer membrane (14-15 mm diam.). The complete cells were rested for one day prior to commencing charge/discharge cycling at a c/50 rate on a battery test station (Maccor, USA) with the cells kept at constant temperature in an oven.

[0157] Ionic Conductivity (S/cm) of Various Ternary Polymer Electrolyte Films as a Function of Temperature

TABLE-US-00001 TABLE 1 PEO-DA + x wt % P14 TFSI + 0.6 mol/kg LiTFSI 20% 30% 40% T/ C. Cell 1 Cell 2 Cell 1 Cell 2 Cell 1 Cell 2 22 2.5E06 2.1E06 1.4E05 1.3E05 3.0E05 2.4E05 32 7.6E06 5.6E06 3.4E05 3.2E05 6.0E05 6.7E05 40 1.4E05 1.1E05 6.9E05 n.a. 1.0E04 1.2E04 40.sup.a 1.3E05 1.3E05 7.5E05 6.3E05 1.1E04 1.2E04 50 2.6E05 2.0E05 1.4E04 1.3E04 2.1E04 1.9E04 50.sup.b 2.5E05 1.8E05 1.4E04 1.1E04 2.2E04 1.8E04 40.sup.a 1.4E05 9.6E06 7.9E05 7.1E05 n.a. 1.2E04 32 7.6E06 5.9E06 4.8E05 4.4E05 6.7E05 7.5E05 22.sup.a n.a. n.a. 1.7E05 n.a. 2.5E05 3.3E05 .sup.aafter 48 h, .sup.bafter 24 h

TABLE-US-00002 TABLE 2 PEO-DA + x wt % P13-FSI + 1.0 mol/kg LiTFSI 30% 40% T/ C. Cell 1 Cell 2 Cell 1 Cell 2 22 C. 1.0E05 1.3E05 3.5E05 4.4E05 32 C. 2.8E05 2.3E05 n.a. n.a. 40 C. 4.8E05 5.2E05 1.4E04 n.a. 50 C. 7.0E05 1.1E04 n.a. 2.0E04 40 C..sup.a 3.9E05 6.1E05 n.a. 1.6E04 32 C. 2.5E05 3.6E05 n.a. 1.2E04 22 C..sup.a 9.2E06 n.a. n.a. 1.2E04 a: after 48 h, b: after 24 h a: after 48 h, b: after 24 h

TABLE-US-00003 TABLE 3 PEO-PDA + 30 wt % P13-FSI + 0.6 mol/kg LiTFSI 23 6.5E06 32 2.2E05 40 4.0E05 50 7.2E05 50 7.1E05 40 3.4E05 33 1.7E05 21 8.8E06

TABLE-US-00004 TABLE 4 PEO-PMMA + 15 wt % P14TFSI + 0.6 mol/kg LiTFSI T/ C. 22 9.5E05 33 1.9E04 40 2.8E04 50 5.0E04

TABLE-US-00005 TABLE 5 PEO-PMMA + 15 wt % P13FSI + 0.6 mol/kg LiFSI T/ C. 22 1.9E05 34 5.0E05 35 5.5E05 40 7.6E05 50 1.0E04

TABLE-US-00006 TABLE 6 PEO-PMMA + 15 wt % P13FSI + 1.0 mol/kg LiFSI T/ C. 22 1.8E04 34 4.3E04 40 5.0E04 50 9.5E04

[0158] Additional Information Relating to the Cyclability of the Polymeric Electrolyte in a Lithium Battery

[0159] Under inert conditions, standard coin cells were assembled with lithium iron phosphate (LFP) cathode foil discs (10.5 mm diam.) and lithium metal foil discs (12 mm diam.) and a pre-fabricated ternary composite polymer membrane (14-15 mm diam.). The complete cells were rested for one day prior to commencing charge/discharge cycling on a battery test station (Maccor).

[0160] ClausesPreferred Arrangements

[0161] 1. A process for forming a conformal film of conducting polymer onto one or more surfaces of a substrate by polymerising onto the one or more surfaces in a single step one or more conducting polymer precursors including one or more monomers in the presence of conductivity enhancing additives comprising one or more ionic liquids and one or more optional ionic dopants.

[0162] 2. The process of clause 1, wherein the conducting polymer precursors and the conductivity enhancing additives are simultaneously present at the substrate's surface when surface binding of the conformal polymer film onto the substrate surface take places.

[0163] 3. The process of clause 1 or clause 2, wherein the conducting polymer precursors and conductivity enhancing additives are provided to the surface in the form of a single (one) solution comprising the one or more monomers, and the one or more optional ionic dopants, which may be dissolved or dispersed in the one or more ionic liquid.

[0164] 4. The process of clause 3, wherein the single (one) solution consists essentially of: the one or more monomers, the one or more ionic liquids and the one or more optional ionic dopants.

[0165] 5. The process of any one of the preceding clauses, wherein the ionic liquid:monomer concentration ratio is sufficient to solubilise the one or more monomers, and/or the optional one or more ionic dopants, when present.

[0166] 6. The process of any one of the preceding clauses, wherein the liquid:monomer concentration ratio is such that substantially all of the ionic liquid and/or dopant is incorporated/entrained in the polymer, wherein preferably, at least 80-90%, and more preferably 90%-100% of the ionic liquid and/or dopant used becomes entrained within the polymer.

[0167] 7. The process of any one of the preceding clauses, wherein the monomer is a diacrylate monomer, the ionic liquid concentration is up to 40 wt % (based on total amount of monomer and ionic liquid) or wherein the monomer is a monoacrylate, the ionic liquid concentration is up to 20 wt % (based on total amount of monomer and ionic liquid).

[0168] 8. The process of any one of the preceding clauses, wherein the surface is a polarisable substrate capable of holding a charge when a suitable potential is applied thereto.

[0169] 9. The process of any one of the preceding clauses, wherein the substrate is selected from the group consisting of: a metal, a metal alloy, a semi-conductor, an electrode or a material typically used in energy storage devices including batteries and capacitors, an electronically conducting polymer, such as polyaniline, polyacrylonitrile, polythiophene, polypyrrole, or derivatives thereof.

[0170] 10. The process of any one of the preceding clauses, wherein the conducting polymer is surface bound to the substrate.

[0171] 11. The process of clause 10 wherein the conducting polymer is surface bound to the substrate by polymerisation initiation on a polarised surface to which potential is applied via an electrografting process.

[0172] 10. The process of any one of the preceding clauses, wherein the polymer is a solid ionically conducting polymer.

[0173] 11. The process of any one of the preceding clauses, wherein the conformal film has a substantially uniform thickness that does not deviate from the mean thickness by any more than 10% and/or the conducting polymer is substantially pin-hole free.

[0174] 15. The process of any one of the preceding clauses wherein the conducting polymer is a homopolymer or a copolymer.

[0175] 16. The process of any one of the preceding clauses wherein in addition to the one or more monomers, the one or more of the conductivity enhancing additives comprise at least one polymerisable functional group and/or one or more hydrophilic, hydrophobic, or other reactive groups, pH responsive groups, emissive, absorptive, fluorescent groups.

[0176] 17. The process of clause 16, wherein the polymerisable functional group is selected from selected from the group consisting of acrylate, vinyl, styrene, acrylonitrile, olefin and/or other polymerisable groups which may be optionally substituted with groups such as alkyl groups, or one or more ionisable or cross linkable functional groups such as COOH or NH.sub.2

[0177] 18. The process of any one of the preceding clauses wherein the ionic dopants are selected from ionisable compounds, including inorganic salts, such as metal salts, MX, where M is selected from the group consisting of Li, Na, K, Be, Mg, Ca, B, Al, and Zn; and where X is a negatively charged ion (anion) selected from the group consisting of: TFSI, FSI, PF.sub.6, BF.sub.4, CF.sub.3SO.sub.3, (Alkyl)BF.sub.3, (Alkyl).sub.nB(CN).sub.4-n, where n is from to 4.

[0178] 19. The process of any one of the preceding clauses wherein the one or more ionic liquids comprising an organic cation selected from the group consisting of: quarternary alky pyrrolidinium, alky piperidinium, alkyl ammonium, alkyl imidazolium, alkyl boronium, and alkyl phosphonium or any other cation which allows for battery operation; and organic anion selected from OTf, TFSI, FSI, or B(CN).sub.4.

[0179] 20. A process for forming a solid polymer electrolyte onto one or more surfaces of a substrate comprising the steps of:

[0180] activating the surface of the substrate to facilitate formation of the polymer thereon, surface binding the polymer onto the surface by polymerising in a single step one or more solid polymer electrolyte precursors onto the modified substrate surface,

[0181] wherein the one or more polymer electrolyte precursors consisting essentially of one or more polymerisable monomers in one or more ionic liquid solvents and one or more ionic dopants.

[0182] 21. A conducting polymer precursor solution for forming a conformal film of conducting polymer onto one or more surfaces of a substrate in a single step, the solution consisting essentially of one or more monomers, one or more ionic liquids, and optionally one or more ionic dopants being a metal salt.

[0183] 22. A conducting polymer precursor solution according to clause 21, wherein the ionic liquid:monomer concentration ratio is sufficient to solubilise the one or more monomers, and/or the optional one or more ionic dopants, when present, yet is such that substantially all of the ionic liquid is incorporated/entrained in the polymer.

[0184] 23. A product obtainable by the process of any one of clauses 20 to 22, preferably having an ionic conductivity of at least 110.sup.5 S/cm at ambient temperature.

[0185] 24. An energy storage device comprising the product of clause 23 as an electrolyte and/or separator of a battery and/or a photovoltaic device.

[0186] 25. The energy storage device of clause 25 wherein the device is a microbattery, for example, a Li polymer battery.

[0187] 26. Use of the product of clause 23 or the energy storage device of clause 24 or 25 in an application selected from a coating application, membrane technology, corrosion or other protecting technologies, a microsensing application, for example, a wireless smart sensor for swarm sensing for environmental monitoring; biomedical applications including use as an artificial membrane and as a modified surface on a medical device and/or implant, preferable to increase biocompatibility and as a battery in medical implants requiring a power source; environmental applications; photovoltaic applications; as a dielectric material in electrochemical capacitors; as modified surfaces for chemical and electrochemical sensors and biosensors; fuel cells and electrolysis membranes; as a modified surfaces in microelectronics and MEMS industry; as a surface modifier for conducting glasses; as a surface modifier without the ionic dopant in general where ionic conduction is not required; in energy storage for microrobotics or for implantable devices; energy harvesting devices and microsupercapacitors, or in methods for method for applying an ionically conducting polymer to conductive surfaces.