ELECTROCHEMICAL BATTERY WITH A BIPOLAR ARCHITECTURE COMPRISING A MATERIAL COMMON TO ALL OF THE ELECTRODES AS ELECTRODE ACTIVE MATERIAL

Abstract

A battery with a bipolar architecture that comprises two terminal current collectors between which a stack of n electrochemical cells is arranged, n being an integer at least equal to 2, wherein: each electrochemical cell comprises a positive electrode, a negative electrode and an electrolytic component arranged between the positive electrode and the negative electrode; the n electrochemical cells are separated from one another by (n1) bipolar current collectors; and wherein the positive electrode and the negative electrode of each electrochemical cell comprise a common active material as active material, which is a redox-active organic compound comprising, respectively, at least one group able to capture electrons and at least one group able to donate electrons.

Claims

1.-13. (canceled)

14. A battery with a bipolar architecture which comprises two terminal current collectors between which a stack of n electrochemical cells is disposed, n being an integer at least equal to 2, wherein: each electrochemical cell comprises a positive electrode, a negative electrode and an electrolytic constituent disposed between the positive electrode and the negative electrode; the n electrochemical cells are separated from each other by (n−1) bipolar current collectors; and wherein the positive electrode and the negative electrode of each electrochemical cell comprise, as an active material, a common active material, which is an organic redox compound comprising, respectively, at least one group capable of capturing electrons and at least one group capable of donating electrons.

15. The battery according to claim 14, wherein the redox compound is a redox compound, in which the group(s) capable of capturing electrons is/are: conjugated carbonyl groups; carboxylate groups; disulphide groups; azo groups; imide groups; or heteroatomic groups; and/or in which the group(s) capable of donating electrons are: enol or enolate groups; nitroxide groups; thioether groups; or aromatic amine groups.

16. The battery according to claim 14, wherein the redox compound is a compound comprising both at least one group selected from among conjugated carbonyl groups, carboxylate groups, disulphide groups and at least one group selected from among enol or enolate groups, nitroxide groups and thioether groups.

17. The battery according to claim 14, wherein the redox compound is a quinone compound substituted by at least one substituent comprising at least one group capable of donating electrons.

18. The battery according to claim 14, wherein the redox compound is a quinone compound selected from among benzoquinone compounds, naphthoquinone compounds and anthraquinone compounds, these compounds comprising at least one substituent comprising at least one group capable of donating electrons.

19. The battery according to claim 14, wherein the redox compound is a quinone compound in the enolate form, substituted by at least one group capable of capturing electrons.

20. The battery according to claim 19, wherein the redox compound is a benzoquinone compound in the enolate form substituted by at least one carboxylate group.

21. The battery according to claim 20, wherein the redox compound is a compound of the following formula (VIII): ##STR00021## wherein X.sup.1 to X.sup.4 represent, independently of each other, a cation and X.sup.5 and X.sup.6 represent, independently of each other, a hydrogen atom or a —SO.sub.3H group.

22. The battery according to claim 14, wherein the negative electrodes and the positive electrodes of the battery further comprise electronic conductive additives.

23. The battery according to claim 14, wherein the negative electrodes and the positive electrodes are gelled electrodes.

24. The battery according to claim 23, wherein the gelled electrodes comprise a composite material comprising a polymeric matrix of at least one gelling polymer (FF) in contact with a liquid electrolyte, the electrode active material, the liquid electrolyte being confined within the polymeric matrix.

25. The battery according to claim 14, wherein the electrolytic constituent is a liquid electrolyte confined within a gelled polymer membrane.

26. The battery according to claim 25, wherein the gelled polymer membrane comprises an organic portion comprising at least one fluorinated polymer (F) comprising at least one repeating unit resulting from the polymerisation of a fluorinated monomer and at least one repeating unit resulting from the polymerisation of a monomer comprising at least one hydroxyl group and comprising an inorganic portion formed, entirely or partly, of one or more oxide(s) of at least one element M selected from among Si, Ti and Zr and combinations thereof.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0210] Other advantages and features of the invention will appear from the following complementary detailed description, which is given as an illustration of the invention and which refers to the appended figures wherein:

[0211] FIG. 1, already discussed, schematically represents a longitudinal sectional view of a conventional example of a battery with a bipolar architecture;

[0212] FIG. 2 is a graph illustrating the evolution of the potential U (in V vs Li.sup.+/Li) as a function of the specific capacitance C (in mAh.Math.g.sup.−1) for 6 consecutive cycles (respectively curve 1 for cycle 1, curve 2 for the cycle 2, curve 3 for cycle 3, curve 4 for cycle 4, curve 5 for cycle 5 and curve 6 for cycle 6) of the button cell illustrated in Example 1;

[0213] FIG. 3 is a graph illustrating the evolution of the potential U (in V vs Li.sup.+/Li) as a function of the specific capacitance C (in mAh.Math.g.sup.−1) for 6 consecutive cycles (respectively curve 1 for cycle 1, curve 2 for the cycle 2, curve 3 for cycle 3, curve 4 for cycle 4, curve 5 for cycle 5 and curve 6 for cycle 6).

DETAILED DESCRIPTION OF PARTICULAR EMBODIMENTS

Example 1

[0214] In this example, the preparation of a lithium battery with a bipolar architecture in accordance with the invention is described involving the following steps: [0215] Preparation of the active material; [0216] 2) Preparation of the gelled electrodes; [0217] 3) Preparation of the gelled membrane; [0218] 4) Preparation of the battery.

[0219] Preparation of the Active Material

[0220] First of all, the biredox organic active material intended to be part of the constitution of the electrodes is prepared, this material corresponding to the following formula:

##STR00019##

[0221] with M representing magnesium.

[0222] To do so, 5.2 g of dihydroxyterephthalic acid are dispersed in 500 mL of water, to which 1.53 g of magnesium hydroxide are added. The suspension is stirred for 48 hours at room temperature before removing the water under reduced pressure. A beige powder is obtained with a substantial yield.

[0223] Afterwards, 1 g of the powder obtained before is dispersed in 25 mL of degassed water, to which 2 equivalents of lithium hydroxide are added under an inert atmosphere. The mixture is stirred for 16 hours with evaporation of the water under reduced pressure. A yellow powder is obtained with a substantial yield. It is treated under vacuum at 235° C. for 48 hours.

[0224] 2—Preparation of the Gelled Electrodes

[0225] For the preparation of the inks intended for the preparation of the electrodes, the same gelling polymer is used, whether for the positive electrode or the negative electrode. This consists of the polymer comprising repeating units resulting from the polymerisation of vinylidene fluoride (96.7% by mole), acrylic acid (0.9% by mole) and hexafluoropropene (2.4% by mole) and having an intrinsic viscosity of 0.30 L/g in dimethylformamide at 25° C. This polymer is referred to hereinbelow as “Polymer 1”. The latter is incorporated with the other ingredients intended for the manufacture of the electrodes in the form of an acetone solution in which 10% of polymer 1 has been dissolved at 60° C. This solution is cooled down to room temperature and introduced into a glove box under an argon atmosphere (O.sub.2<2 ppm, H.sub.2O<2 ppm).

[0226] More specifically, active material, the preparation of which is explained in paragraph 1 hereinbelow, and C-Nergy® C65 carbon are added to the solution of anhydrous acetone at 99.9% purity comprising Polymer 1 and a liquid electrolyte composed of a mixture of carbonate solvents (ethylene carbonate/propylene carbonate 1/1) and LiPF.sub.6(1M), so as to obtain a mass ratio (m.sub.electrolyte/(m.sub.electrolyte+m.sub.polymer 1))*100 equal to 85.7%, whereby the resulting ink ultimately comprises 65% active material, 15% C-Nergy® C65 carbon and 20% Polymer 1.

[0227] The ink is deposited by coating over an aluminium substrate (more specifically, an aluminium foil with a 20 μm thickness).

[0228] As many gelled electrodes as necessary for making up the bipolar battery are prepared in accordance with this protocol.

[0229] Moreover, gelled electrodes prepared in accordance with this protocol have been tested in a button cell with, as a separator, a separator comprising the superposition of a sheet of Viledon® and a sheet of Celgard®, the separator being soaked in a liquid electrolyte comprising a mixture of carbonate solvents (ethylene carbonate/propylene carbonate, 1/1) and LiPF.sub.6(1M).

[0230] The button cell thus obtained is subjected to a high-voltage galvanostatic test covering voltages ranging from 2.5 to 4V vs Li.sup.+/Li at a constant current corresponding to a C/10 regime, the active material of the gelled electrode undergoing in this context an oxidation of the lithium enolate groups into carbonyl groups (or in other words, undergoing delithiation), this oxidation or delithiation may be schematised by the following equation:

##STR00020##

[0231] the results of this test being reported in FIG. 2 illustrating the evolution of the voltage U0 (in V vs Li.sup.+/Li) as a function of the specific capacitance C (in mAh.Math.g.sup.−1) for 6 consecutive cycles (respectively curve 1 for cycle 1, curve 2 for cycle 2, curve 3 for cycle 3, curve 4 for cycle 4, curve 5 for cycle 5 and curve 6 for cycle 6).

[0232] Starting from cycle 2, the curves are superimposed, which demonstrates the stability of the gelled electrodes and, what is more, the shape of the curves also demonstrates the ability of the gelled electrodes to behave, starting from the same active material, as an electrode capable of donating electrons.

[0233] 3—Preparation of the Gelled Membrane

[0234] The gelled membrane consists of an organic/inorganic hybrid copolymer based on modified PVdF-HFP including methacrylic branches (PVdF-HEA-HFP) in which a sol-gel reaction is performed from tetraethoxysilane (TEOS).

[0235] It is obtained by coating a polymeric solution over a polyethylene terephthalate (PET) substrate then peeled off this substrate because it is self-supporting.

[0236] Preparation of the Polymeric Solution

[0237] To do so, 10 g of a copolymer comprising repeating units resulting from the polymerisation of vinylidene fluoride (VDF), 2-hydroxyethyl acrylate (HEA) and hexafluoropropene (HFP), this polymer being called PVdF-HEA-HFP (VDF 96.8% by mole-HEA 0.8% by mole and HFP 2.4% by mole) and having an intrinsic viscosity of 0.08 g/L are introduced into a 300 mL double-walled synthesis reactor inerted beforehand with argon and then 67 mL of anhydrous acetone at 99.9% purity are added. The mixture is mechanically stirred for 30 min at 60° C. under a flow of argon. Afterwards, 0.10 g of dibutyltin dilaurate (DBTL) are added and the resulting mixture is stirred for 90 minutes at 60° C. under a stream of argon. Afterwards, 0.40 g of 3-(triethoxysilyl)propyl isocyanate (TSPI) are added and the mixture is stirred for 90 minutes at 60° C. under a stream of argon. 37.50 g of electrolyte with composition identical to that used for the electrodes is added and the mixture is stirred for 30 min at 60° C. under a stream of argon. Afterwards, 2.50 g of formic acid are added and the mixture is stirred for 30 minutes at 60° C. under a stream of argon. Finally, 3.47 g of tetraethoxysilane are added and the mixture is stirred for 30 minutes at 60° C. under a stream of argon.

[0238] b) Preparation of the Membranes from the Polymeric Solution

[0239] Once prepared, the polymeric solution is transferred to a tight vial in an anhydrous room (dew point −20° C. to 22° C.). It is then coated using an R2R (“Roll to roll slot die coating machine, Ingecal tailored made”) coating machine, the solution being introduced into the machine at room temperature but in a controlled environment with a dew point of −20° C. to 22° C. The use settings of the machine are as follows: [0240] Line speed: 1 m/min; [0241] Drying section: 40° C. for the first and second areas; 50° C. for the third area and 60° C. for the fourth area; [0242] Opening of the slot in extrusion: 300 μm, which allows obtaining a membrane of about 50 μm deposited over a polyethylene terephthalate (PET) substrate.

[0243] The membrane strip thus obtained is then stored in a heat-sealed tight bag while waiting to proceed with the assembly of the bipolar battery.

[0244] 4—Preparation of the Bipolar Battery

[0245] Two electrodes prepared in accordance with the protocol of paragraph 2 are joined via their current collector substrate to form a two-face electrode comprising a bipolar current collector substrate resulting from the joining of the two current collector substrates and, on one face of the bipolar current collector substrate, an electrode and on the opposite face of the bipolar current collector substrate, another electrode.

[0246] Two membranes with the dimensions 34 mm×34 mm are cut from the membrane strip prepared beforehand and deposited over the 2 faces of the bipolar current collector coated with the electrodes. Two electrodes prepared in accordance with the protocol of paragraph 2 are then placed against the membranes, opposite each electrode with an opposite polarity of the bipolar current collector, these two electrodes making up the terminal electrodes. The two-compartment bipolar electrochemical core is then secured in a flexible package.

[0247] The bipolar battery thus obtained is subjected to a galvanostatic test covering voltages ranging from 1 to 6 V vs Li.sup.+/Li at a constant current corresponding to a C/10 regime, the results of this test being reported in FIG. 3 illustrating the evolution of the potential U (in V vs Li.sup.+/Li) as a function of the specific capacitance C (in mAh.Math.g.sup.−1) for 6 consecutive cycles (respectively, curve 1 for cycle 1, curve 2 for cycle 2, curve 3 for cycle 3, curve 4 for cycle 4, curve 5 for cycle 5 and curve 6 for cycle 6).

[0248] Starting from cycle 2, the curves are similar, which demonstrates the stability of the gelled electrodes and, what is more, the shape of the curves demonstrates the ability of the gelled electrodes to behave, starting from the same active material, both as a positive electrode and as a negative electrode.