ELECTRODE COATED WITH REDOX POLYMERS CONTAINING DIONE UNITS, PREPARATION METHOD AND USES THEREOF

Abstract

An electrode comprising a support made of a conductor or semiconductor, at least one nanostructure made of a conductor or semiconductor, on at least one of the support surfaces, a layer of redox polymer containing dione units deposited onto the at least one nanostructure. The present disclosure also concerns processes for preparing an electrode coated with such a redox polymer and electrode-based energy storage device containing such a coated electrode.

Claims

1. Electrode comprising: a support made of a conductor or semiconductor, at least one nanostructure made of a conductor or semiconductor, on at least one of the support surfaces, a layer of redox polymer deposited onto the at least one nanostructure, wherein the redox polymer is of formula (I): ##STR00021## in which n is an integer selected from the range 2 to 10,000; X.sub.1 and X.sub.2, which are identical or different, each independently is selected from the group consisting of S, O and Se; R.sub.1, R.sub.2, R.sub.3 and R.sub.4, which are identical or different, each independently is selected from the group consisting of a hydrogen, a halogen, an optionally substituted alkyl, an optionally substituted alkylaryl and an optionally substituted arylalkyl; G.sub.1 and G.sub.2, which are identical or different, each independently represents a group of formula (II): ##STR00022## in which represents the covalent bond linking the G.sub.1 or G.sub.2 group with the dione unit in the polymer of formula (I); X.sub.3 and X.sub.4, which are identical or different, each independently is selected from the group consisting of S, O and Se; R.sub.5, R.sub.6, R.sub.7 and R.sub.8, which are identical or different, each independently is selected from the group consisting of a hydrogen atom, a halogen atom, an optionally substituted alkyl group, an optionally substituted arylalkyl group and an optionally substituted alkylaryl group or R.sub.5 and R.sub.6 and/or R.sub.7 and R.sub.8 form together a bridging group; a is selected from the group consisting of 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14 and 15, and b and c, which are identical or different, each independently is selected from the group consisting of 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14 and 15.

2. Electrode according to claim 1, wherein X.sub.1 and X.sub.2 both represent S.

3. Electrode according to claim 1, wherein the groups R.sub.1 and R.sub.2 are identical and advantageously represent a hydrogen atom, an optionally substituted alkyl group, an optionally substituted arylalkyl group or an optionally substituted alkylaryl group.

4. Electrode according to claim 1, wherein the groups R.sub.3 and R.sub.4 are identical and advantageously both represent a hydrogen.

5. Electrode according to claim 1, wherein, in said G.sub.1 group and/or said G.sub.2 group, X.sub.3 and X.sub.4 both represent S.

6. Electrode according to claim 1, wherein, in said G.sub.1 group and/or said G.sub.2 group, R.sub.5 and R.sub.8 represent a hydrogen atom and R.sub.6 and R.sub.7 are identical and represent an optionally substituted alkyl group.

7. Electrode according to claim 1, wherein, in said G.sub.1 group and/or said G.sub.2 group, R.sub.5 and R.sub.6 form together a bridging group and R.sub.7 and R.sub.8 form together a bridging group, these bridging groups being identical.

8. Electrode according to claim 1, wherein the redox polymer of formula (I) is the redox polymer of formula (I) in which X.sub.1=X.sub.2=S; R.sub.1=R.sub.2=an octyl radical; R.sub.3=R.sub.4=H; G.sub.1=G.sub.2=a group of formula (II) in which b=c=0 and a=1 with X.sub.3=S, R.sub.6=H and R.sub.5=an octyl radical; the redox polymer of formula (I) in which X.sub.1=X.sub.2=S; R.sub.1=R.sub.2=an octyl radical; R.sub.3=R.sub.4=H; G.sub.1=G.sub.2=a group of formula (II) in which a=b=c=1 with X.sub.3=X.sub.4=S, R.sub.5=R.sub.8=a hydrogen atom and R.sub.6=R.sub.7=an octyl radical; the redox polymer of formula (I) in which X.sub.1=X.sub.2=S; R.sub.1=R.sub.2=an octyl radical; R.sub.3=R.sub.4=H ; G.sub.1=G.sub.2=a group of formula (II) in which b=c=0 and a=1 with X.sub.3=S and R.sub.5 and R.sub.6 together form a bridging group of formula O(CH.sub.2).sub.2O; or the redox polymer of formula (I) in which X.sub.1=X.sub.2=S; R.sub.1=R.sub.2=an octyl radical; R.sub.3=R.sub.4=H; G.sub.1=G.sub.2=a group of formula (II) in which b=c=0 and a=1 with X.sub.3=S and R.sub.5 and R.sub.6 together form a bridging group of formula O(CH.sub.2)C(CH.sub.3).sub.2(CH.sub.2)O.

9. Electrode according to claim 1, wherein said support is made of silicon and advantageously doped silicon.

10. Electrode according to claim 1, wherein said nanostructure is made of silicon and advantageously doped silicon.

11. Device for storing and releasing electrical energy comprising at least one electrode as defined in claim 1.

12. Device for storing and releasing electrical energy comprising at least two electrodes as defined in claim 1.

13. Device for storing and releasing electrical energy according to claim 11, wherein said device is a battery, a dielectric capacitor, a supercapacitor or a hybrid system that can act simultaneously as a capacitor or a battery.

14. Method for preparing an electrode as defined in claim 1, said method comprising the steps consisting in: a) preparing a redox polymer of formula (I), and b) depositing said redox polymer onto the at least one nanostructure present on at least one surface of the support.

15. Method for preparing an electrode as defined in claim 1, said method comprising the steps consisting in: a) putting into contact the support presenting on at least one of its surface a nanostructure with a solution comprising different or identical monomers of formula (VII): ##STR00023## in which X.sub.1, X.sub.2, R.sub.1, R.sub.2, R.sub.3 and R.sub.4 are as defined in claim 1 and G.sub.1 and G.sub.2, which are identical or different, each independently represents a group of formula (VIII): ##STR00024## in which , X.sub.3, X.sub.4, R.sub.5, R.sub.6, R.sub.7 and R.sub.8 are as defined in claim 1, b) electropolymerizing said monomers whereby redox polymer of formula (I) is formed.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0111] FIG. 1 presents the characterization using cyclic voltammetry experiments obtained while characterizing by electrochemistry monomers implemented in the invention i.e. FL136 (FIG. 1A) and FL137 (FIG. 1B).

[0112] FIG. 2 concerns the characterization of FL137 coated SiNWs, optionally compared with SiNWs. FIG. 2A presents SEM image of SiNWs and FIG. 2B presents SEM image of FL137 coated SiNWs with the corresponding EDX analysis. FIG. 2C presents the cyclic voltammogram curve of 1.5 mM FL137 in CH.sub.2Cl.sub.2 with 0.1 M NBu.sub.4PF.sub.6 on highly doped silicon substrates. Initial and final potentials: 2.20 V; reversal potential: 1.40 V. Scan rate: 50 mVs.sup.1. FIG. 2D presents the CV curve of a FL137-coated SiNW electrode at a scan rate of 5 mVs.sup.1 in a 3-electrochemical cell using PYR.sub.13TFSI as electrolyte. Initial and final potential:

1.50 V; reversal potential: 0.50 V.

[0113] FIG. 3 presents the electrochemical performance of SiNW-based symmetric supercapacitor and of a FL137-coated SiNW-based symmetric supercapacitor at a cell voltage of 3V using N.sub.1114 BTA as electrolyte. FIG. 3A presents the CV curves of SiNWs-based supercapacitor (plain line) and hybrid supercapacitor (bold line) at a scan rate of 2Vs.sup.1. FIG. 3B presents the CV curves of FL137-coated SiNW-based symmetric supercapacitor at different scan rates from 0.4 to 2Vs.sup.1. Arrow indicates the increase of scan rate. FIG. 3C presents the cycling stability of the device performed using 25,000 complete galvanostatic charge-discharge cycles at a current density of 1 mA.cm.sup.2. Inset shows an example of the cycle.

DETAILED DISCUSSION OF PARTICULAR EMBODIMENTS

I. Methods for the Synthesis of Monomers

I.1. Chemicals

[0114] All reagents and chemicals were purchased from Aldrich or Acros and used as received, except for THF which was distilled over sodium-benzophenone prior to use. Thin layer chromatography was performed on silica gel-coated aluminium plates with a particle size of 2-25 m and a pore size of 60 . Silica from Merck (70-230 mesh) was used for flash chromatography. 5,5-dimethyl-2-(4-octylthien-2-yl)[1,3,2]dioxaborinane and [E-(5-(3-octylthien-2-yl-vinyl)-(3-octylthien-2-yl)]-trimethyltin were prepared according to published procedures [24].

I.2. Characterisation Methods

[0115] All synthesized products were identified by .sup.1H and .sup.13C NMR spectroscopy, as well as by elemental analysis. NMR spectra were recorded in chloroform-d, or acetone-d6 containing tetramethylsilane (TMS) as internal standard, on a Bruker AC200 spectrometer.

[0116] Elemental analyses (C, H, N, and S) were carried out by the Analytical Service of the CNRS (Vernaison, France) or by CRMPO at the University of Rennes 1.

[0117] Ultraviolet-visible (UV-vis) absorption spectra were recorded on a HP 8452A spectrometer (wavelength range 190-820 nm).

II. Synthesis of Monomers FL136 and FL137

II.1. 3-octyl-5-trimethylstannylthiophene

[0118] ##STR00013##

[0119] To a stirred solution of 3-octylthiophene (7.50 g, 38.19 mmol) in 100 mL of freshly distilled THF at 78 C. was added dropwise a solution of n-butyllithium (n-BuLi) (2.5 M, 16.8 mL, 42 mmol). The resulting solution was stirred for 45 min and warmed to 50 C. The mixture was cooled at 78 C. and trimethyltin chloride (8.40 g, 42 mmol) dissolved in 20 mL of THF was added quickly.

[0120] The resulting mixture was allowed to warm to room temperature over 80 min and then it was poured into water, extracted with diethyl ether and the organic extracts were washed with saturated aqueous solution of NH.sub.4Cl. After drying and filtration, the filtrate was concentrated under reduced pressure to give 13.80 g of organostannane. Due to the high toxicity of organostannane compound, the crude product was merely titrated (90% of purity) by NMR and used without further purification.

[0121] .sup.1H NMR (200 MHz, CDCl.sub.3) (ppm): 7.20 (d, J=0.8 Hz, 1 H), 7.01 (d, J=0.8 Hz, 1 H), 2.64 (t, 3J=7.4 Hz, 2 H), 1.62 (tbr, 2 H), 1.35-1.25 (m, 10 H), 0.88 (t, 3J=6.8 Hz, 3 H), 0.35 (s, 9 H).

II.2. Diethyl-2,5-bis[4-octylthien-2-yl]-1,4-benzenedicarboxylate

[0122] ##STR00014##

[0123] Diethyl-2,5-dibromo-1,4-benzenedicarboxylate (2.50 g, 6.57 mmol) and 3-octyl-5-trimethylstannylthiophene (7.20 g, 18.94 mmol) were dissolved in anhydrous DMF (75 mL) and the resulting mixture was purged 10 min with Ar.

[0124] Separately Pd(OAc).sub.2 (0.15 g, 0.66 mmol) and PPh.sub.3 (0.70 g, 2.65 mmol) were placed in 5 mL of freshly distilled THF and stirred 10 min under argon. After the formation of a yellow precipitate, the catalyst was transferred in the DMF solution and the mixture was heated to 100 C. overnight. The mixture was then filtered through celite and DMF was removed under reduced pressure. The crude product was purified by column chromatography (silica gel, hexane/CH.sub.2Cl.sub.2, 7:3) to afford 3.85 g (98%) of a transparent oil.

[0125] .sup.1H NMR (200 MHz, CDCl.sub.3) (ppm): 7.76 (s, 2 H), 6.96 (d, 4J=1.4 Hz, 2 H), 6.91 (d, 4J=1.4 Hz, 2 H), 4.21 (q, 3J=7.1 Hz, 4 H, OCH2), 2.60 (t, 3J=8.0 Hz, 4H), 1.65-1.55 (m, 4 H), 1.45-1.25 (m, 20 H), 1.16 (t, 3J=7.1 Hz, 6 H, OCH2CH3,), 0.92-0.85 (m, 6 H). Elemental analysis, found (calcd): C, 70.51 (70.78); H, 8.19 (8.25).

II.3. 2,5-bis[4-octylthien-2-yl]-1,4-benzenedicarboxylic (FL46)

[0126] ##STR00015##

[0127] Elemental analysis, found (calcd): C, 69.35 (69.28); H, 7.50 (7.63).

II.4. 3,8-dioctyl-4,9-dihydro-s-indaceno[1,2-b:5,6-6-b]dithiophene-4,9-dione (FL127)

[0128] ##STR00016##

[0129] 2,5-bis[4-octylthien-2-yl]-1,4-benzenedicarboxylic (1.0 g, 1.80 mmol) was dissolved in 70 mL of anhydrous CH.sub.2Cl.sub.2 under argon. Then oxalyl chloride (1.80 mL, 20.5 mmol) and 0.40 mL of DMF, were added and the mixture was stirred 12 h at room temperature. The solvent was removed under reduced pressure to obtain the crude 2,5-bis[4-octylthien-2-yl]-1,4-benzenedicarboxylic acid dichloride which was used without further purification.

[0130] The product was dissolved in 80 mL of anhydrous CH.sub.2Cl.sub.2 under argon, then cooled to 0 C. and a suspension of AlCl.sub.3 (0.72 g, 5.41 mmol) in 80 mL of anhydrous CH.sub.2C1.sub.2 was added dropwise. The mixture was maintained at 0 C. for 30 min and then allowed to warm to room temperature. After stirring 3 h at room temperature, the reaction mixture was poured into ice water and 1 M hydrochloric acid and extracted with chloroform. The organic layer was washed with water, dried over Na.sub.2SO.sub.4, filtered and concentrated under reduced pressure. Column chromatography (silica gel, hexane/CHCl.sub.3, 7:3) afforded 0.78 g of a blue solid (84%).

[0131] .sup.1H NMR (200 MHz, CDCl.sub.3) (ppm): 7.18 (s, 2 H), 6.79 (s, 2 H), 2.71 (t, 3J=7.3 Hz, 4 H), 1.69-1.62 (m, 3J=7.3 Hz, 4 H), 1.40-1.26 (m, 20 H), 0.92-0.84 (m, 6 H). 13C NMR (CDC13, 50 MHz): (ppm): 189.07 (2C=O), 161.15 (2C), 143.85 (2C), 143.54 (2C), 142.49 (2C), 142.38 (2C), 127.57 (2C), 117.09 (2C), 34.75 (2C), 32.28 (2C), 32.24 (2C), 32.20 (2C), 32.10 (2C), 31.28 (2C), 25.55 (2C), 17.02 (2C). Elemental analysis, found (calcd): C, 73.95 (74.09); H, 7.33 (7.38).

II.5. 2,7-dibromo-3,8-dioctyl-4,9-dihydro-s-indaceno[1,2-b:5,6-b]dithiophene-4,9-dione (FL128)

[0132] ##STR00017##

[0133] To a solution of 3,8-dioctyl-4,9-dihydro-s-indaceno[1,2-b:5,6-b]dithiophene-4,9-dione (1.0 g, 1.92 mmol) in 30 mL of CHCl.sub.3 and 30 mL of AcOH, was added N-Bromosuccinimide (1,04 g, 2.92 mmol) in small portions over a period of 15 min. The reaction mixture was stirred 10 h at room temperature and then it was poured into water and extracted with CHCl.sub.3. The organic layer was washed with NaHCO.sub.3 and dried over Na.sub.2SO.sub.4.

[0134] The crude product was concentrated under reduced pressure and precipitated from hexane. The filtrate was washed with methanol and acetone and then dried under vacuum to give 1.26 g of a greenish solid (97%).

[0135] .sup.1H NMR (200 MHz, C.sub.2D.sub.2Cl.sub.4) (ppm): 7.14 (s, 2H), 2.71 (t, 3J=7.0 Hz, 4H), 2.61 (t, 3J=7.3 Hz, 4H), 1.67-1.50 (m, 4H), 1.25-1.10 (m, 20H), 0.95-0.85 (m, 6H). 13C NMR (C2D2C14, 50 MHz): (ppm): 185.28 (2C=O), 156.45 (2C), 139.83 (2C), 139.66 (4C), 138.18 (2C), 114.64 (2C), 113.64 (2C), 32.06 (2C), 29.50 (2C), 29.42 (2C), 29.37 (2C), 29.07 (2C), 27.46 (2C), 22.87 (2C), 14.36 (2C).

II.6. 2,7-bis(4-octylthien-2-yl)-3,8-dioctyl-4,9-dihydro-s-indaceno[1,2-b:5,6-b]dithiophene-4,9-dione (FL136)

[0136] ##STR00018##

[0137] This product was synthesized starting from 2,7-dibromo-3,8-dioctyl-4,9-dihydro-s-indaceno[1,2-b:5,6-b]dithiophene-4,9-dione (0.65 g, 0.96 mmol) and 3-octyl-5-trimethylstannylthiophene (2.5 eq) according to the Stille palladium-catalyzed coupling procedure described above.

[0138] After usual work up, the product was purified by column chromatography (silica gel, hexane/CHCl.sub.3, 7:3) to give 0.62 g (72%) of a green-blue solid.

[0139] .sup.1H NMR (200 MHz, CDC1.sub.3) (ppm): 7.14 (s, 2H), 6.98 (d, 4J=1.2 Hz, 2H), 6.94 (d br, 2H), 2.85 (t, 3J=6.8 Hz, 4H), 2.61 (t, 3J=7.3 Hz, 4H), 1.75-1.52 (m, 8H), 1.45-1.20 (m, 40H), 0.95-0.80 (m, 12H). 13C NMR (CDCl3, 50 MHz): (ppm): 186.57 (2C=O), 155.31 (2C), 143.83 (2C), 140.55 (2C), 140.33 (2C), 139.43 (2C), 136.37 (4C), 134.36 (2C), 127.81 (2C), 120.91 (2C), 114.07 (2C), 31.89 (4C), 30.42 (4C), 29.57 (4C), 29.43 (4C), 29.34 (4C), 29.28 (4C), 22.68 (4C), 14.13 (4C). Elemental analysis, found (calcd): C, 73.85 (74.12); H, 8.14 (8.22); S, 13.95 (14.13).

II.7. 2,7-bis(5-[(E)-1,2-bis(3-octylthien-2-yl)ethylene])-3,8-dioctyl-4,9-dihydro-s-indaceno[1,2-b:5,6-b]dithiophene-4,9-dione (FL137)

[0140] ##STR00019##

[0141] This product was synthesized starting from 2,7-dibromo-3,8-dioctyl-4,9-dihydro-s-indaceno[1,2-b:5,6-b]dithiophene-4,9-dione (0.50 g, 0.74 mmol) and [E-(5-(3-octylthien-2-yl-vinyl)-(3-octylthien-2-yl)]-trimethyltin (2.2 eq.) according to the Stille palladium-catalyzed coupling procedure described above. After usual work up, the product was purified by column chromatography (silica gel, hexane/CHCl3, 8:2) to give 0.62 g (63%) of a dark greenish solid.

[0142] .sup.1H NMR (200 MHz, CDCl.sub.3) (ppm): 7.12 (s, 2H), 7.09 (d, 3J=5.1 Hz, 2H), 6.96 (s br, 4H), 6.90 (s, 2H), 6.86 (d, 3J=5.1 Hz, 2H), 2.91 (t, 3J=7.4 Hz, 4H), 2.75-2.55 (m, 3J=7.4 Hz, 8H), 1.75-1.50 (m, 12H), 1.45-1.15 (m, 60H), 0.90-0.80 (m, 18H). 13C NMR (CDC13, 50 MHz): (ppm): 186.53 (2C=0), 155.05 (2C), 141.29 (2C), 141.21 (2C), 140.73 (2C), 140.41 (2C), 139.38 (2C), 137.18 (2C), 136.53 (2C), 136.27 (2C), 136.07 (2C), 131.56 (2C), 129.89 (2C), 128.69 (2C), 122.96 (2C), 119.86 (2C), 118.53 (2C), 114.02 (2C), 31.90 (6C), 30.93 (2C), 30.82 (2C), 29.89 (2C), 29.63 (2C), 29.47 (2C), 29.44 (2C), 29.39 (4C), 29.34 (2C), 29.33 (2C), 29.29 (4C), 28.46 (2C), 28.39 (2C), 27.16 (2C), 22.69 (6C), 14.13 (6C). Elemental analysis, found (calcd): C, 74.25 (74.83); H, 8.53 (8.52).

III. Synthesis of 2,7-bis(2,3-dihydrothieno[3,4-b][1,4]dioxin-5-yl)-3,8-dioctyl-s-indaceno[1,2-b:5,6-b]dithiophene-4,9-dione (DJ313)

[0143] ##STR00020##

[0144] Under argon, 3,4-Ethylenedioxythiophene (63 mg, 0.44 mmol) was dissolved in distilled THF (8 mL) then n-BuLi (0.20 mL, 0.49 mmol) was added at 78 C. The solution was stirred for an hour at 50 C. before adding a n-hexane solution of trimethyltin chloride (0.49 mL, 0.49 mmol) at 78 C. The solution was allowed to reach room temperature and stirred for 2 hours. The reaction was quenched with water and the organic phase was extracted with n-hexane, dried on Na.sub.2SO.sub.4, filtered and concentrated under vacuum. The resulting oil was engaged without any further purification in a Stille coupling with 4-2,7-dibromo-3,8-dioctyl-s-indaceno[1,2-b:5,6-b]dithiophene-4,9-dione. Under argon, solids stannic, 2,7-dibromo-3,8-dioctyl-s-indaceno[1,2-b:5,6-b]dithiophene-4,9-dione (100 mg, 0.15 mmol), tris(dibenzylideneacetone)dipalladium (5.4 mg, 6 mol) and tri(o-tolyl)phosphine (3.6 mg, 12 mol) were dissolved in anhydrous toluene (8 mL) and refluxed for 14 h. The mixture was then poured into HCl (2 M). The organic phase was extracted with diethyl ether, washed with HCl (2 M), dried over Na.sub.2SO.sub.4 and concentrated. The crude solid was chromatographed on silica using petroleum ether/CHCl.sub.3 1:1 as eluent to afford green solid (118 mg, 0.10 mmol, 70%).

[0145] 1H NMR (CDCl3, 400 MHz): =7.18 (s, 2H), 6.44 (s, 1H), 4.31 (m, 8H), 2.86 (t, J=7.8Hz, 4H), 1.72-1.60 (m, 4H), 1.45-1.20 (m, 24H), 0.90 (t, 1H, J=6.8Hz).

[0146] 1H NMR (CDC13, 400 MHz): =186.66, 156.78, 141.48, 140.54, 139.83, 139.69, 139.04, 137.74, 132.72, 114.09, 99.81, 65.00, 64.46, 31.90, 29.87, 29.62, 29.35, 29.26, 27.33, 22.68, 14.126.

IV. Characterization of FL136 and F1137 by Electrochemistry

[0147] Cyclic voltammetry experiments were performed in an argon glove box, using a one-compartment electrolytic cell with a platinum disk working electrode (7 mm.sup.2 surface area), a platinum counter electrode and an Ag/0.01 mol.L.sup.1 AgNO.sub.3 reference electrode. The electrolyte consisted of 0.1 mol.L.sup.1 tetrabutylammonium tetrafluoroborate (Bu.sub.4NBF.sub.4) solution in dichloromethane, to which 2.10.sup.3 mol.L.sup.1 of FL136 or 1.5.10.sup.3 mol.L.sup.1 of FL137 were added. The results of this characterization are presented in FIG. 1A for FL136 and at FIG. 1B for FL137.

V. Preparation of Poly(FL136) and Poly(FL137) by Oxidative Polymerization

V.1. Poly(FL136)

[0148] A solution of 145 mg of anhydrous ferric chloride (0.89 mmol) in a mixed solvent consisting of 4 mL of nitromethane and 5 mL of chloroform was added dropwise to a solution of FL136 (200 mg, 0.2204 mmol) in 30 mL of freshly distilled and degassed chloroform. The addition was performed at 0 C. with constant stirring over a period of 90 min. At the end of the addition, the mixture was warmed to 10 C. and was maintained at this temperature for an additional period of 60 min. The reaction mixture was then allowed to warm to room temperature and stirred for 5 h. Subsequently, it was concentrated by pumping under vacuum and then precipitated in 100 mL of methanol. The crude polymer was then dissolved in 50 mL of chloroform and washed four times with a 0.1 M aqueous solution of ammonia (150 mL each time). In the next step the polymer was stirred for 48 h with the same aqueous solution.

[0149] As-synthesized polymer usually contains small amounts of dopants of unidentified chemical nature and requires further dedoping. The dedoping was achieved by washing the chloroform solution of the polymer with an EDTA aqueous solution (0.05 M, 200 mL). The polymer was then washed with water twice and acetone and then dried under vacuum to give 185 mg (93%) of a dark powder. The product is then fractionated with a Sohxlet apparatus using chloroform and chlorobenzene.

[0150] Size exclusion chromatography analysis of the batch: Mn[kDa eq. PS]=3.7643 kDa eq. PS; Mw[kDa eq. PS]=4.9664 kDa eq. PS; I=Mw/Mn=1.3194; Mw up to[kDa eq. PS]20.0 kDa eq. PS.

V.2. Poly(FL137)

[0151] The same procedure as described above was employed using 200 mg of FL137 and 97 mg of iron chloride. The polymer was obtained as a dark powder (150 mg).

[0152] Size exclusion chromatography analysis of the batch: Mn[kDa eq. PS]=3.3648 kDa eq. PS; Mw[kDa eq. PS]=4.1824 kDa eq. PS; I=Mw/Mn=1.2430; Mw up to[kDa eq. PS] 15.0 kDa eq. PS.

VI. Electrodes Made Using FL137

VI.1. Preparation of Electrodes Using FL137

[0153] Growth of SiNWs : Highly doped SiNWs electrodes with a length of approximately 20 m and a diameter of 50 nm were grown in a CVD reactor (EasyTube3000 First Nano, a Division of CVD Equipment Corporation) by using the vapor-liquid-solid (VLS) method via gold catalysis on highly doped p-Si(111) substrate using an optimal deposition procedure, which has been previously detailed [25]. Briefly, the SiNWs were grown from a colloidal gold catalyst performed at 600 C., under 6 Torr total pressure, with 40 sccm (standard cubic centimeters) of SiH.sub.4, 100 sccm of B.sub.2H.sub.6 gas (0.2% B.sub.2H.sub.6 in H.sub.2) for p doping, 100 sccm of HCl gas and 700 sccm of H.sub.2 as supporting gas.

[0154] Electropolymerization of FL137 on SiNWs: FL137 films were electrochemically deposited from a CH.sub.2Cl.sub.2 solution containing 0.1 M tetrabutylammonium hexafluorophosphate (NBu.sub.4PF.sub.6) and 1.5 mM FL137 as the monomer using an AUTOLAB PGSTAT 302 N potentiostat-galvanostat. The electropolymerization was conducted in a 3-electrode electrochemical cell. SiNWs was employed as the working electrode, a Pt wire was used as the counter electrode and the nonaqueous Ag/Ag.sup.+ reference electrode was composed of a silver wire immersed in a 10 mM silver trifluoromethanesulfonate (AgTf) solution in N-methyl-N-propylpyrrolidinium bis(trifluoromethylsulfonyl)imide (PYR.sub.13 TFSI). The electrochemical deposition of FL137 was carried out by potentiostatic methods using a constant potential (1 V) controlled by the chronocoulometry technique (Total polymerization charge of 20 mC) in an argon-filled glove box with oxygen and water levels less than 1 ppm. After the electrochemical deposition, the electrodes were washed in acetone and dried with a N.sub.2 flow before the electrochemical characterization.

VI.2. Characterization of Electrodes thus Prepared

[0155] Morphological characterization: The morphology of the resulting SiNWs and hybrid SiNWs electrodes was examined by scanning electron microscopy. A Zeiss Ultra 55 scanning microscope operating at an accelerating voltage of 10 kV was used.

[0156] Electrochemical characterization: FL137-coated SiNWs electrode was evaluated in a 3-electrode cell configuration using PYR.sub.13 TFSI as electrolyte. The hybrid electrode was employed as the working electrode, a Pt wire was used as the counter electrode and the nonaqueous Ag/Ag.sup.+ reference electrode was composed of a silver wire immersed in a 10 mM silver trifluoromethanesulfonate (AgTf) solution in PYR.sub.13 TFSI.

[0157] Performance and configuration of the device: Symmetric micro-supercapacitors were designed from hybrid nanostructured electrodes made of FL137-coated SiNWs as mentioned in the previous section. A homemade two-electrode supercapacitor cell was built by assembling two hybrid nanostructured material-based electrodes (1 cm.sup.2) separated by a Whatman glass fiber paper separator soaked with butyl-trimethyl ammonium bis(trifluoromethylsulfonyl)imide (N.sub.1114 BTA) as electrolyte. Cyclic voltammetry (CV) and galvanostatic charge-discharge cycles were performed using a multichannel VMP3 potentiostat/galvanostat with Ec-Lab software (Biologic, France). All measurements were carried out using N.sub.1114 BTA as electrolyte in an argon-filled glove box with oxygen and water levels less than 1 ppm at room temperature.

[0158] Results: The morphology of SiNWs and FL137-coated SiNW electrodes was analyzed by scanning electron microscopy as displayed in FIGS. 2A and 2B. FIG. 2A shows the view of SiNWs grown by CVD on silicon substrates. The length of SiNWs was estimated to be 20 m and the density of SiNWs was determined to be 3.10.sup.9 nanowires per cm.sup.2 with a diameter of 50 nm according to the inventors' previous works [26]. The functionalization of SiNW electrodes using FL137 as an electroactive pseudo-capacitive material was carried out using an electrochemical deposition as mentioned in the previous section. Thus, FL137 was deposited electrochemically on SiNWs using a potentiostatic method at a constant potential. As a result, a uniform and homogeneous nanometric FL137 coating was deposited onto SiNWs with a smooth globular morphology as illustrated in FIG. 2B. The confirmation of the polymer coating was corroborated by EDX analysis (S and O). FIG. 2C presents the cyclic voltammogramm of 1.5 mM FL137 in CH.sub.2Cl.sub.2 with 0.1 M NBu.sub.4PF.sub.6on highly doped silicon substrates (0.4 cm.sup.2), which was recorded at a scan rate of 50 mV s.sup.1 using a potential range from 2.00 V to 1.4 V. As can be seen, a pair of oxidation-reduction peaks were detected, which are associated with the oxidation and reduction of FL137. The reduction peak is ascribed with the de-intercalation of anion (TFSI.sup.) from the FL137 film due to the reduction of the polymer from the oxidized to the neutral state, whereas the oxidation peak reflects the intercalation of anions into the polymeric structure. The electrochemical response of FL137-coated SiNWs was evaluated in a 3-electrode cell configuration in presence of PYR.sub.13TFSI as displayed in FIG. 2D. FIG. 2D displays a CV curve evidencing its excellent electrochemical behaviour as well as an outstanding electroactivity and storage charge (85 F/g).

[0159] FIG. 3 shows the electrochemical performance of a symmetric supercapacitor based on FL137-coated SiNW electrodes using N.sub.1114 BTA as electrolyte within a voltage cell of 3 V. As can be seen in FIG. 3A, the hybrid device shows a higher capacitance than SiNW-based supercapacitor due to the pseudocapacitive effect induced by the polymer coating on SiNW surface. This phenomena was demonstrated at wide range of scan rates from 0.2 to 2 Vs.sup.1 reflecting an excellent capacitive behaviour (FIG. 3B).

[0160] Concerning one of the most important criteria in a supercapacitor, cycling stability, the lifetime of the device was evaluated by applying successive galvanostatic cycles at a high current density of 1 mA.cm.sup.2. Thus, the device was able to retain more than 80% after 25000 complete galvanostatic cycles demonstrating its enormous potential in terms of lifespan (FIG. 3C).

[0161] This cycling stability value was compared with similar systems based on electroactive conducting polymers. Consequently, PEDOT-coated SiNW and PPy-coated Silicon Nanotree supercapacitors reflected a loss of specific capacitance of 20% and 30% after 3,500 and 10,000 charge-discharge cycles respectively [9]. The use of electroactive conducting polymers for supercapacitor devices is limited due to their poor cycling stability (typically a few thousand cycles).

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