New lithium-doped Pernigraniline-based materials

Abstract

The present invention relates to a new lithium-doped Pernigraniline-based material, a method for the preparation thereof, its use in various applications, an electrode comprising said lithium-doped Pernigraniline-based material and its preparation method, a membrane comprising said lithium-doped Pernigraniline-based material and its preparation method, and an electrochemical storage system comprising said electrode.

Claims

1. A lithium-doped Pernigraniline-based material (PN-Li), comprising: at least one polymer chain formed by the succession of C.sub.6H.sub.4 rings and nitrogen atoms, each nitrogen atom being linked in para position relative to each C.sub.6H.sub.4 ring; n repeating units; a total amount X of lithium cations (Li.sup.+); an average amount x of lithium cations (Li.sup.+) per repeating unit, with x=X/n; a total amount Y of anions (A.sup.m); an average amount y of charge provided by anions (A.sup.m) per repeating unit, with y=mY/n; a charge q of each repeating unit, a total charge Q of the polymer chain, with Q={circumflex over ()}q.sub.i mYX since Q is compensated by the charges of Li.sup.+ and A.sup.m; Q/n represents the formal oxidation state and Q/n =y-x; and wherein said PN-Li responds to the following formula (I): ##STR00012## in which: * 4n500,000, * q is equal to 1, 0 or +1, * the mean atomic ratio hydrogen/nitrogen (H/N) for each repeating unit is such that 4H/N<4.5, * 1Q/n<0, *0.5x1, *0y0.5.

2. A method for the preparation of a lithium-doped Pernigraniline-based material (PN-Li) as defined in claim 1 or a composition (C) comprising PN-Li as defined in claim 1, wherein it comprises at least the following steps: 1) putting into contact Polyaniline (P) or a composition (C) comprising at least Polyaniline (P), with a deprotonation solution to obtain a reaction mixture, said deprotonation solution comprising: at least one aprotic solvent, at least one lithium salt which is soluble in said aprotic solvent, at least one lithiated organic compound (LiOC.sub.1) or precursors (PR.sub.1, PR.sub.2) of said lithiated organic compound LiOC.sub.1, said LiOC.sub.1 or (PR.sub.1, PR.sub.2) being soluble in said aprotic solvent, and said LiOC.sub.1 being a strong Bronsted base able to deprotonate the amine groups present in Polyaniline (P), 2) leaving the reaction mixture with no mixing or with a moderate mixing, 3) recovering lithium-doped Pernigraniline-based material (PN-Li) or a composition (C) comprising at least one lithium-doped Pernigraniline-based material (PN-Li).

3. The method according to claim 2, wherein the deprotonation solution further comprises an organic compound OC.sub.2 which is soluble in said aprotic solvent and which comprises an alkene functional group.

4. The method according to claim 2, wherein the lithiated organic compound LiOC.sub.1 is selected from lithium amides, lithium enolates, lithium ester enolates, lithium acetylides, organolithium compounds, and mixtures thereof

5. The method according claim 2, wherein the precursor PR.sub.1 of the lithiated organic compound LiOC.sub.1 is metallic lithium (Li) and the precursor PR.sub.2 of the lithiated organic compound OC.sub.1 is any one of the following conjugated acids of OC.sub.1: an amine, a ketone, an ester, an alkyne or an alkyl halide.

6. A positive electrode material comprising: at least one polymeric binder, optionally a material conferring electronic conduction other than PN-Li, optionally an active material other than PN-Li, and wherein it further comprises a lithium-doped Pernigraniline material PN-Li as defined in claim 1.

7. The positive electrode material according to claim 6, wherein said positive electrode material is a lithium battery-type positive electrode material comprising with respect to the total weight of the positive electrode material: from 60 weight % to 98 weight % of PN-Li, from 1 weight % to 15 weight % of a material conferring electronic conduction other than PN-Li, and from 1 weight % to 15 weight % of a polymeric binder; and wherein said positive electrode material does not comprise any other active material than PN-Li.

8. The positive electrode material according to claim 6, wherein said positive electrode material is a supercapacitor-type positive electrode material comprising with respect to the total weight of the positive electrode material: from 35 weight % to 60 weight % of PN-Li, from 15 weight % to 60 weight % of a material conferring electronic conduction other than PN-Li having a high specific surface area ranging from 400 m.sup.2/g to 3000 m.sup.2/g, and from 1 weight % to 15 weight % of a polymeric binder; and wherein said positive electrode material does not comprise any other active material than PN-Li.

9. The positive electrode material according to claim 6, wherein it is a lithium battery-type composite positive electrode material comprising from 60 weight % to 96 weight % of an active material other than PN-Li with respect to the total weight of the positive electrode material.

10. A method for the preparation of a positive electrode material as defined in claim 6, wherein said method comprises at least the following steps: A) preparing a composition comprising Polyaniline (P), at least one polymeric binder, optionally a material conferring electronic conduction other PN-Li, and optionally an active material other than PN-Li, and B) preparing a composition comprising at least one lithium-doped Pernigraniline-based material (PN-Li) from the composition of step A), according to the following steps: 1) putting into contact Polyaniline (P) or a composition (C) comprising at least Polyaniline (P), with a deprotonation solution to obtain a reaction mixture, said deprotonation solution comprising: at least one aprotic solvent, at least one lithium salt which is soluble in said aprotic solvent, at least one lithiated organic compound (LiOC.sub.1) or precursors (PR.sub.1 PR.sub.2) of said lithiated organic compound LiOC.sub.1, said LiOC.sub.1 or (PR.sub.1 PR.sub.2) being soluble in said aprotic solvent, and said LiOC.sub.1 being a strong Brnsted base able to deprotonate the amine groups present in Polyaniline (P), 2) leaving the reaction mixture with no mixing or with a moderate mixing, 3) recovering lithium-doped Pernigraniline-based material (PN-Li) or a composition (C) comprising at least one lithium-doped Pernigraniline-based material (PN-Li).

11. A lithium battery comprising: a positive electrode material, a negative electrode material, a separator which acts as electrical insulator and allows the transport of ions, and a non-aqueous electrolyte comprising at least one lithium salt and an aprotic solvent, and wherein the positive electrode material is a battery-type positive electrode material or a battery-type composite positive electrode material as defined in claim 7.

12. A supercapacitor comprising: a positive electrode material, a negative electrode material, a separator which acts as electrical insulator and allows the transport of ions, and a non-aqueous electrolyte comprising at least one lithium salt and an aprotic solvent, and wherein the positive electrode material is a supercapacitor-type positive electrode material as defined in claim 8.

13. A free-standing membrane comprising with respect to the total weight of the membrane: from 2 weight % to 15 weight % of a polymeric binder, and wherein it further comprises from 85 weight % to 98 weight % of PN-Li as defined in claim 1.

14. A method for the preparation of a membrane as defined in claim 13, wherein said method comprises at least the following steps: i) preparing a composition comprising Polyaniline (P) and at least one polymeric binder in the form of a film, ii) preparing a composition comprising at least one lithium-doped Pernigraniline-based material (PN-Li) from the composition of step i), according to the following steps: 1) putting into contact Polyaniline (P) or a composition (C) comprising at least Polyaniline (P), with a deprotonation solution to obtain a reaction mixture, said deprotonation solution comprising: at least one aprotic solvent, at least one lithium salt which is soluble in said aprotic solvent, at least one lithiated organic compound (LiOC.sub.1) or precursors (PR.sub.1 PR.sub.2) of said lithiated organic compound LiOC.sub.1, said LiOC.sub.1 or (PR.sub.1 PR.sub.2) being soluble in said aprotic solvent, and said LiOC.sub.1 being a strong Brnsted base able to deprotonate the amine groups present in Polyaniline (P), 2) leaving the reaction mixture with no mixing or with a moderate mixing, 3) recovering lithium-doped Pernigraniline-based material (PN-Li) or a composition (C) comprising at least one lithium-doped Pernigraniline-based material (PN-Li).

15. A method for the preparation or the modification of a lithium-doped Pernigraniline-based material (PN-Li) as defined in claim 1, wherein it comprises at least one step of submitting to a charge a battery having a positive electrode material, a negative electrode material, a separator which acts as electrical insulator and allows the transport of ions, and a non-aqueous electrolyte comprising at least one lithium salt and an aprotic solvent, or a supercapacitor having a positive electrode material, a negative electrode material, a separator which acts as electrical insulator and allows the transport of ions, and a non-aqueous electrolyte comprising at least one lithium salt and an aprotic solvent.

16. An active material in electrodes, or a binder, or a conducting agent, in any one of batteries, supercapacitors, electronic and/or optoelectronic devices like solar cells, photoconductors, light-emitting or electrochromic devices, field effect transistors, electromagnetic radiation absorbers, gas sensors, separation membranes, antistatic coatings, conducting molecular wires and anticorrosion coatings comprising: a lithium-doped Pernigraniline-based material PN-Li as defined in claim 1.

Description

EXAMPLES

[0236] The starting materials used in the examples which follow, are listed below:

[0237] Lithium hexafluorophosphate (LiPF.sub.6): Purolyte, Novolyte, 24 99.99% purity;

[0238] Dimethyl carbonate (DMC): Purolyte, Novolyte, 99% purity;

[0239] Ethylene carbonate (EC): Purolyte, Novolyte, 99% purity;

[0240] N,N-diphenyl-p-phenylenediamine: Alfa Aesar, 97% purity;

[0241] Metallic lithium used for the synthesis: Aldrich, 99.9% purity;

[0242] Lithium metal used as a negative electrode: Aldrich, 99.9% purity;

[0243] Emeraldine base (EB): Aldrich, molecular weight (MW)50,000;

[0244] Polytetrafluoroethylene (PTFE): Aldrich;

[0245] Vapour grown carbon fibers (VGCF): Showa Denko;

[0246] N-methyl-2-pyrrolidinone (NMP): Aldrich, 99% purity;

[0247] LiFePO.sub.4 (LFP): Umicore;

[0248] Carbon coated LiFePO.sub.4 (LFP/C): Umicore, 2.5 wt % of carbon content;

[0249] Ethanol (EtOH): Carlo Erba, 96% EtOH in volume;

[0250] Reduced graphene oxide (rGO): xGnP, xGsciences;

[0251] Conductive Carbon SuperP : Timcal;

[0252] Poly(vinylenedifluoride) (PVdF): Aldrich;

[0253] These starting materials were used as received from the manufacturers, without additional purification.

[0254] EB nanofibers were synthetized according to the method reported in Jimnez et al. [Macromol. Rapid Comm., 2009, 30(6), 418-422].

[0255] The charge/discharge and cyclic voltammetry investigations were carried out using a VMP3 Scanning Probe Electrochemistry (SPE) platform commercialized by Bio-Logic Science Instruments, and an EC-Lab software commercialized by Bio-Logic Science Instruments.

[0256] Transmission electron microscopy (TEM) was performed by using a H9000NAR 300 kV microscope commercialized by Hitachi.

[0257] XPS analyses were performed by using a Kratos Axis Ultra spectrometer. The X-ray source is Al K working at 1486.6 eV.

Example 1

Preparation of a Lithium-Doped Pernigraniline Material PN-Li According to the Present Invention (i.e. First Object of the Invention) and Prepared According to the Process of the Present Invention (i.e. Second Object of the Invention)

[0258] Inside an argon-filled glove box, 2.1 g of LiPF.sub.6 were dissolved in 10 ml of propylene carbonate. To the resulting solution, 160 mg of N,N-diphenyl-p-phenylenediamine and 100 l of styrene were added. Then, a piece of 0.5 g of metallic lithium was introduced in the preceding solution. Then, 250 mg of polyaniline powder in the emeraldine base state (EB) was introduced in the preceding solution. The reaction was left with no agitation for 16 hours. The lithium was then removed from the reaction mixture and said reaction mixture was filtrated. A solid was recovered and washed twice with 20 ml of dimethyl carbonate (DMC) to yield 239 mg of the desired material PN-Li (95% yield).

[0259] FIG. 1 represents a Fourier transform infrared spectroscopy (FTIR) of PN-Li (curve with a plain line), and to provide a comparison of Emeraldine base EB (curve with a dotted line). FIG. 1 shows the absorbance as a function of the wavenumber (in cm.sup.1). It can be concluded that the PN-Li material maintains the structure of a polyaniline, since the main vibration modes of EB are preserved with variations in frequency and relative intensity.

[0260] The FTIR analysis has been performed using the potassium bromide (KBr) Pellet Method with an apparatus Vertex 70 commercialized by Bruker).

[0261] FIG. 2 represents the conductivity of PN-Li (in S/m) as a function of the frequency (in GHz). The conductivity has been measured on 7 mm diameter pressed pellets of PN-Li material using simultaneously an impedance analyzer (Agilent 4294 from 40 to 1.1.Math.10.sup.7 Hz) and a network analyzer (HP 8510 from 4.5.Math.10.sup.7 to 10.sup.9 Hz).

Example 2

Preparation of a Lithium Battery (Fifth Object of the Invention) Comprising an Electrode Material E1-PN-Li According to the Present Invention (i.e. Third Object of the Invention) Prepared According to the Process of the Present Invention (i.e. Fourth Object of the Invention)

[0262] Inside an argon-filled glove box, 2.1 g of LiPF.sub.6 were dissolved in 10 ml of a dimethyl carbonate and ethylene carbonate mixture in a 1:1 volume proportion. To the resulting solution, 160 mg of N,N-diphenyl-p-phenylenediamine and 100 l of styrene were added. Then, a piece of 0.5 g of metallic lithium was introduced in the preceding solution. Then, 250 mg of a mixture of EB, polytetrafluoroethylene (PTFE) and vapour grown carbon fibers (VGCF) in 90:5:5 weight proportions was embedded in a stainless steel wire mesh current collector and the resulting embedded stainless steel wire was introduced in the preceding solution. The reaction was left undisturbed for 16 hours. The lithium was then removed from the reaction mixture and said reaction mixture was filtrated. A solid was recovered and washed twice with 20 ml of DMC to yield the desired positive electrode material E1-PN-Li embedded in the stainless steel wire mesh current collector (E1-PN-Li/current collector). The positive electrode material E1-PN-Li produced had a loading of mg of PN-Li/cm.sup.2 approximately and the thickness of the whole (E1-PN-Li/current collector) was about 280 m.

[0263] A lithium battery (Swagelok type cell) comprising:

[0264] the obtained positive electrode material E1-PN-Li embedded in the stainless steel wire mesh current collector (5 mg of E1-PN-Li material),

[0265] lithium metal as a negative electrode material deposited onto a copper current collector; the thickness of the lithium metal was about 400 m,

[0266] a solution of 1M LiPF.sub.6 in a mixture of EC and DMC in a 1:1 volume proportion as an electrolyte, and

[0267] a Whatman glass fiber separator provided by GE Healthcare

[0268] was assembled inside a glove box commercialized by Jacomex.

[0269] FIG. 3 represents the electrochemical characterization of the E1-PN-Li electrode material by cyclic voltammetry. FIG. 3 shows the current density (in microAmpere per milligram, A/mg) as a function of the potential (in Volts, V) versus the couple Li.sup.+/Li.sup.0 (i.e. vs Li.sup.+/Li.sup.0 potential). In FIG. 3, the lithium battery was subjected to a cyclic voltammetry test between 4.3 V and 2.5 V with negative electrode as reference potential, at a scan speed of 0.1 mV/s.

[0270] FIG. 4 represents the specific capacity obtained during repeated cycling of the battery between 2.5 and 4.3 V at a 250 A current for charge and discharge. FIG. 4 shows the specific capacity (in mAh/g.sub.pN-Li) as a function of the cycle number.

[0271] FIG. 5 represents the specific capacity of the E1-PN-Li electrode material delivered in a sequential discharge test. The electrode is initially charged to 4.3 V and is submitted to successive discharges to 2.5 V at decreasing current values from 15.03 mA to 23.5 A (corresponding to discharge rates decreasing from 20 C to 1/32 C). FIG. 5 shows on the left the potential vs Li.sup.+/Li.sup.0 (in volts, V) as a function of time and on the right the specific capacity (in mAh/g.sub.pN-Li) as a function of time. Values greater than 180 mAh/g at a 1 C rate and of 210 mAh/g at lower rates were obtained.

[0272] FIG. 6 represents the Ragone plot (in double logarithmic scale) of the E1-PN-Li electrode material power density (in W/kg.sub.electrode material) as a function of the electrode material energy density (in Wh/kg.sub.electrode material) during the discharge test described above. This E1-PN-Li electrode material is able to deliver energy density values of 460 Wh/kg.

[0273] To provide a comparative example, an electrode material (E1-EB) was prepared by mixing EB with polytetrafluoroethylene (PTFE) and vapour grown carbon fibers (VGCF) in 90:5:5 weight proportions and by embedding the resulting mixture in a stainless steel wire mesh current collector. This positive electrode material E1-EB is not part of the present invention.

[0274] Then, a lithium battery (Swagelok type cell) comprising:

[0275] the obtained positive electrode material E1-EB embedded in the stainless steel wire mesh current collector (3 mg of E1-EB material); the thickness of the whole (E1-EB/current collector) was about 280 m,

[0276] lithium metal as a negative electrode material deposited onto a copper current collector; the thickness of the lithium metal was about 400 m,

[0277] a solution of 1M LiPF.sub.6 in a mixture of EC and DMC in a 1:1 volume proportion as an electrolyte, and

[0278] a Whatman glass fiber separator provided by GE Healthcare

[0279] was assembled inside a glove box commercialized by Jacomex.

[0280] FIG. 7 represents the electrochemical characterization of the E1-EB electrode material by cyclic voltammetry. FIG. 7 shows the current density (in A/mg) as a function of the potential (in Volts, V) versus the couple Li.sup.+/Li.sup.0 (i.e. vs Li.sup.+/Li.sup.0 potential). In FIG. 7, the lithium battery was subjected to a cyclic voltammetry test between 4.3 V and 2.5 V by measuring the potential against the negative electrode, at a scan speed of 0.5 mV/s. FIG. 7 shows that there is only one redox transition in EB when it is cycled between 2.5 V and 4.3 V, whereas in PN-Li there are two (cf. FIG. 3).

Example 3

Preparation of a Lithium Battery (i.e. Fifth Object of the Invention) Comprising a Composite Electrode Material CE1-PN-Li According to the Present Invention (i.e. Third Object of the Invention) Prepared According to the Process of the Present Invention (i.e. Fourth Object of the Invention)

[0281] 5 mg of EB were dispersed in 5 ml of N-methyl-2-pyrrolidinone. Then, 195 mg of LiFePO.sub.4 were added to the dispersion and the resulting mixture was stirred for 2 hours. Then, 25 ml of ethanol were added dropwise to the resulting mixture while stirring. The obtained mixture was filtered. A solid was recovered, washed with ethanol, and dried to yield LiFePO.sub.4 particles coated with EB (also called LFP/EB material).

[0282] FIG. 8 represents a TEM image of the obtained LFP/EB material. FIG. 8 shows the thin coating of EB covering the LiFePO.sub.4 particles.

[0283] Inside an argon-filled glove box, 1.5 g of LiPF.sub.6 were dissolved in 10 ml of a 1:1 mixture in volume of dimethyl carbonate and ethylene carbonate. To the resulting solution, 1 mg of N,N-diphenyl-p-phenylenediamine and 5 l of styrene were added. Then, a piece of 0.2 g of metallic lithium was introduced in the preceding solution. Then, 5 mg of a mixture of LFP/EB material, PTFE, and VGCF in 90:5:5 weight proportions was embedded in a stainless steel wire mesh current collector and the resulting embedded stainless steel wire was introduced in the preceding solution. The reaction was left undisturbed for 16 hours. The lithium was then removed from the reaction mixture and said reaction mixture was filtrated. A solid was recovered and washed twice with 20 ml of DMC to yield the desired positive composite electrode material CE1-PN-Li.

[0284] To provide a comparative example, a composite electrode material (CE1-carbon) was prepared by mixing carbon coated LiFePO.sub.4 (LFP/C), PTFE, and VGCF in 90:5:5 weight proportions and by embedding the resulting mixture in a stainless steel wire mesh current collector. This composite positive electrode material is not part of the present invention.

[0285] All the positive electrodes materials produced had a loading of active material (LFP) of 10 mg/cm.sup.2 approximately.

[0286] Two lithium batteries (Swagelok type cell) comprising:

[0287] the obtained positive electrode material CE1-PN-Li embedded in the stainless steel wire mesh current collector (2 mg of CE1-PN-Li material) or the obtained positive electrode material CE1-carbon embedded in the stainless steel wire mesh current collector (2 mg of CE1-carbon),

[0288] lithium metal as a negative electrode material deposited onto a copper current collector; the thickness of the lithium metal was about 400 m,

[0289] a solution of 1M LiPF.sub.6 in a mixture of EC and DMC in a 1:1 volume proportion as an electrolyte, and

[0290] a Whatman glass fiber separator provided by GE Healthcare

[0291] were assembled inside a glove box commercialized by Jacomex.

[0292] FIG. 9 represents the Ragone plot of the electrode power density (in W/kg.sub.electrode material) as a function of the electrode energy density (in Wh/kg.sub.electrode material) for each electrode, when each corresponding battery is subjected to charge-discharge tests between 4.2 V and 2.5 V at decreasing current rates from 20 C to 1/32 C (1 C being equivalent to a current density of 170 mAh/g based on LFP). The CE1-PN-Li composite electrode material (curve with squares and plain line) displays better performance at high discharge rates than the CE1-carbon composite electrode material (curve with circles and dotted line).

Example 4

[0293] Preparation of a Supercapacitor (Sixth Object of the Invention) Comprising an Electrode Material E2-PN-Li According to the Present Invention (i.e. Third Object of the Invention) Prepared According to the Process of the Present Invention (i.e. Fourth Object of the Invention)

[0294] 25 mg of EB were dispersed in 10 ml of NMP. 25 mg of reduced graphene oxide (rGO) were added to the dispersion and the resulting mixture was stirred for 2 hours. 25 ml of ethanol were added dropwise to the resulting mixture while stirring. The obtained mixture was filtered. A solid was recovered, was washed with ethanol, and dried to yield reduced graphene oxide coated with EB (also called rGO/EB material).

[0295] Inside an argon-filled glove box, 1.5 g of LiPF.sub.6 were dissolved in 10 ml of a 1:1 volume mixture of dimethyl carbonate and ethylene carbonate. To the resulting solution, 1 mg of N,N-diphenyl-p-phenylenediamine and 5 l of styrene were added. Then, a piece of 0.2 g of metallic lithium was introduced in the preceding solution. Then, 1.6 mg of a mixture of rGO/EB material, PTFE, and carbon SuperP in 90:5:5 weight proportions was embedded in a stainless steel wire mesh and the resulting embedded stainless steel wire was introduced in the preceding solution. The reaction was left undisturbed for 16 hours. The lithium was then removed from the reaction mixture and said reaction mixture was filtrated. A solid was recovered and washed twice with 20 ml of dimethyl carbonate to yield the desired positive electrode material E2-PN-Li.

[0296] To provide two comparative examples, an electrode material (E2- EB) was prepared by mixing rGO/EB material, PTFE, and carbon SuperP in 90:5:5 weight proportions, and by embedding the resulting mixture in a stainless steel wire mesh current collector; and an electrode material (E2) was prepared by mixing rGO, PTFE, and carbon SuperP in 90:5:5 weight proportions, and by embedding the resulting mixture in a stainless steel wire mesh current collector. These two positive electrodes materials are not part of the present invention.

[0297] Three lithium batteries (Swagelok type cell) comprising:

[0298] the obtained positive electrode material E2-PN-Li embedded in the stainless steel wire mesh current collector (1.77 mg of E2-PN-Li material) or the obtained positive electrode material E2- EB embedded in the stainless steel wire mesh current collector (1.8 mg of E2-EB material) or the obtained positive electrode material E2 embedded in the stainless steel wire mesh current collector (1.75 mg of E2 material),

[0299] lithium metal as a negative electrode material deposited onto a copper current collector; the thickness of the lithium metal was about 400 m,

[0300] a solution of 1M LiPF.sub.6 in a mixture of EC and DMC in a 1:1 volume proportion as an electrolyte, and

[0301] a Whatman glass fiber separator provided by GE Healthcare

[0302] were assembled inside a glove box commercialized by Jacomex.

[0303] All the positive electrodes produced had a loading of material (rGO and PN-Li if it is present) of 10 mg/cm.sup.2 approximately.

[0304] FIG. 10 represents the electrochemical characterization of the E2-PN-Li electrode material (curve with plain line), of the E2-EB electrode material (curve with dotted line) and of the E2 electrode material (curve with dashed line) by cyclic voltammetry. FIG. 10 shows the electrode material specific capacity (in mAh/g) obtained during repeated cycling of the battery between 2.5 and 4.3 V at a scan speed of 1 mV/s as a function of the cycle number.

Example 5

Preparation of a Lithium Battery (Fifth Object of the Invention) Comprising a Composite Electrode Material CE2-PN-Li According to the Present Invention (i.e. Third Object of the Invention) Prepared According to the Process of the Present Invention (i.e. Fourth Object of the Invention)

[0305] Inside an argon-filled glove box, 1.5 g of LiPF.sub.6 were dissolved in 10 ml of a 1:1 volume mixture of dimethyl carbonate and ethylene carbonate. To the resulting solution, 1 mg of N,N-diphenyl-p-phenylenediamine and 5 l of styrene were added. Then, a piece of 0.2 g of metallic lithium was introduced in the preceding solution. Then, 5 mg of a mixture of LFP/EB material prepared in example 3, PTFE, and EB nanofibers in 90:5:5 weight proportions was embedded in a stainless steel wire mesh and the resulting embedded stainless steel wire mesh was introduced in the preceding solution. The reaction was left undisturbed for 16 hours. The lithium was then removed from the reaction mixture and said reaction mixture was filtrated. A solid was recovered and washed twice with 20 ml of DMC to yield the desired positive composite electrode material CE2-PN-Li (99% yield).

[0306] A lithium battery (Swagelok type cell) comprising:

[0307] the obtained positive electrode material CE2-PN-Li embedded in the stainless steel wire mesh current collector (5.5 mg of CE2-PN-Li material, the electrode of the whole (CE2-PN-Li /current collector) was about 280 m,

[0308] lithium metal as a negative electrode material deposited onto a copper current collector; the thickness of the lithium metal was about 400 m,

[0309] a solution of 1M LiPF.sub.6 in a mixture of EC and DMC in a 1:1 volume proportion as an electrolyte, and

[0310] a Whatman glass fiber separator provided by GE Healthcare

[0311] was assembled inside a glove box commercialized by Jacomex.

[0312] The positive electrode produced had a loading of active material (LFP) of 25 mg/cm.sup.2 approximately.

[0313] FIG. 11 represents the Ragone plot of the electrode power density (in W/kg.sub.LFP) as a function of the electrode energy density (in Wh/kg.sub.LFP) for the obtained positive electrode, when the battery is subjected to charge-discharge tests between 4.2 V and 2.5 V at decreasing current rates from 20 C to 1/32 C (1 C being equivalent to a current density of 170 mAh/g based on LFP).

Example 6

Preparation of a Free-Standing Membrane Film MF-PN-Li According to the Present Invention (i.e. Seventh Object of the Invention) and Prepared According to the Process of the Present Invention (i.e. Eighth Object of the Invention)

[0314] A dispersion of 1 mg of poly(vinylenedifluoride) (PVDF) and 19 mg of EB in 1 ml of NMP was prepared by stirring. The mixture was spread on a flat glass substrate with a surface of around 25 cm.sup.2. The deposition was dried for 24 hours at 60 C. to obtain a film. The film was peeled off from the glass substrate by immersion in distilled water and it was dried again to remove water.

[0315] Inside an argon-filled glove box, 1.5 g of LiPF.sub.6 were dissolved in 10 ml of a 1:1 mixture of ethylene carbonate and dimethyl carbonate. To the resulting solution, 2 mg of N,N-diphenyl-p-phenylenediamine and 10 l of styrene were added. Then, a piece of 0.4 g of metallic lithium was introduced in the preceding solution. Then, the film previously prepared (20 mg) was introduced in the preceding solution. The reaction was left undisturbed for 16 hours. The lithium was then removed from the reaction mixture and said reaction mixture was filtrated. A membrane film of PN-Li material was recovered and washed thrice with 50 ml of DMC to yield the desired flexible, resistant and electrically conducting thin (1 m) membrane film MF-PN-Li (21.5 mg).

Comparative Example 7

Preparation of a Lithium-Doped EB (emeraldine Base)

[0316] Inside an argon-filled glove box, 3.038 g of LiPF.sub.6 were dissolved in 20 ml of an equivolume of ethylene carbonate and dimethyl carbonate. To the resulting solution, 10 mg of a polyaniline film in the emeraldine base state (EB) was introduced in the preceding solution. The reaction was left with no agitation for 48 hours at room temperature. The reaction mixture was filtrated. A film was recovered and washed twice with diethyl ether and dry in vacuum at 60 C. for 4 h to yield 18.1 mg of the desired material EB-Li.

[0317] EB-Li is not part of the invention. EB-Li is described in [Manuel et al., Material Research Bulletin, 2010, 45, 265].

[0318] FIG. 12 represents the Nis (nitrogen) region of the XPS analysis of EB-Li (FIG. 12a), and for comparison the Nis region of the XPS analysis of PN-Li (FIG. 12b) and the Nis region of the XPS analysis of EB (FIG. 12c).

[0319] PN-Li is part of the invention and has been obtained according to the procedure described in example 6.

[0320] EB is pure emeraldine base (starting material). It is not part of the invention.

[0321] FIG. 12 shows for each material, the CPS (Counts per second, from the detector of electrons) as a function of the binding energy (in eV). The XPS analyses have been conducted in the same way (i.e. same parameters) for each material.

[0322] FIG. 12 clearly shows that the chemical environment of the nitrogen atoms changes from the starting EB material to the two different materials EB-Li and PN-Li, indicating that the PN-Li material of the present invention does not have the same structure as the ones of EB-Li and EB. More particularly, a new signal at 402 eV is obtained for the PN-Li material.