Use of an oxyhydroxy salt related to the family of lamellar double hydroxides for the design and manufacture of an electrode with a view to storing electrical energy

1. A material for an electrode of an energy storage device having a theoretical electrical energy capacity greater than or equal to 160 Ah/kg, the material comprising at least one compound related to a ferrous-ferric layered double hydroxide (LDH),

said at least one compound comprising at least one divalent cation D II and at least one trivalent cation T III of general formula (I):

[D II 3n(1−x) T III 3nx O 6n H n(7−3x) ] n+ [A n− , m H 2 O] n−   (I)

wherein A n− is an anion of charge n, n having the values 1, 2 or 3,

m is an integer in the range from 1 to 10, and

x is from 0 to 1, excluding 1,

wherein said at least one compound comprises a minimum amount of Fe II of 1%, permitting conversion of Fe II to Fe III .

2. The material according to claim 1 , wherein the material comprises at least one compound of ferrous-ferric oxyhydroxy salt of general formula (II):

[Fe II 3n(1−x) Fe III 3nx O 6n H n(7−3x) ] n+ [A n− ,m H 2 O] n−   (II)

wherein A n− is an anion of charge n, n having the values 1, 2 or 3,

m is an integer in the range from 1 to 10, and

x is from 0 to 1, excluding 1,

it being possible for said ferrous-ferric oxyhydroxy salt to be partially modified by a partial or complete replacement of at least one of its elements.

3. The material according to claim 2 , wherein A n− represents CO 3 2− leading to the formula (III):

[Fe II 6(1−x) Fe III 6x O 12 H 2(7−3x) ] 2+ [CO 3 2− ,3H 2 O] 2−   (III)

in which x is from 0 to 1, excluding 1.

4. The material according to claim 2 , wherein A n− represents CO 3 2− and the available protons H + of the OH − groups are partially or completely replaced with monovalent cations, to give a structure of general formula (IV) in the case of the carbonate in which the protons are replaced with lithium:

[Fe II 6(1−x) Fe III 6x O 12 H 8+6(1−y) Li I 6(y−x) ] 2+ [CO 3 2− ,3H 2 O] 2−   (IV)

in which x is from 0 to 1, excluding 1, and 1≧y≧x.

5. The material according to claim 4 , wherein said monovalent cations are Li + .

6. The material according to claim 2 , wherein A n− represents CO 3 2− and the Fe II is partially replaced with divalent cations.

7. The material according to claim 6 , wherein said divalent cation is Ni 2+ and/or Co 2+ to give a structure of general formula (V) in the case of the carbonate in which the Fe II is replaced with Ni 2+ and the protons H + are not replaced:

[Fe II 6(1−y−x) Ni II 6y Fe III 6x O 12 H 2(7−3x) ] 2+ [CO 3 2− ,3H 2 O] 2−   (V)

in which x is from 0 to 1, excluding 1, and 0<y≦1−x.

8. The material according to claim 2 , wherein A n− represents CO 3 2− and the Fe III is partially or completely replaced with trivalent cations.

9. The material according to claim 8 , wherein said trivalent cation is Al 3+ and/or Co 3+ to give a structure of general formula (VI) in the case of the carbonate in which the Fe III is replaced with Al 3+ , and the Fe II and/or the protons H + are not replaced:

[Fe II 6(1−x) Fe III 2(3x−z) Al III 2z O 12 H 2(7−3x) ] 2+ [CO 3 2− ,3H 2 O] 2−   (VI)

in which x is from 0 to 1, excluding 1, and 0<z≦3x.

10. The material according to claim 2 , wherein said material is in the form of a composite material, and further comprises a binder of oil or paraffin.

11. The material according to claim 10 , wherein said binder is paraffin, and said composite material comprises a carbon matrix mixed with a ferrous-ferric oxyhydroxy salt, the ferrous-ferric oxyhydroxy salt/carbon ratio (w/w) being from about 0.1 to about 100, and the ferrous-ferric oxyhydroxy salt/paraffin ratio (w/w) being from about 1 to about 10.

12. The material according to claim 10 , wherein said binder is oil and said composite material comprises a carbon matrix mixed with the ferrous-ferric oxyhydroxy salt, the ferrous-ferric oxyhydroxy salt/carbon ratio (w/w) being from about 0.1 to about 100, and the ferrous-ferric oxyhydroxy salt/oil ratio (w/w) being from about 1 to about 10.

13. The material according to claim 1 , wherein the theoretical electrical energy capacity of said electrode is equal to 245 Ah/kg, and n is 2, and m is 3.

14. The material according to claim 1 , wherein said material constitutes a cathode or an anode configured to be associated with a corresponding counter-electrode present in the energy storage device.

15. The material according to claim 14 , wherein said counter-electrode possesses an active redox couple having a potential difference greater than 1 V relative to the electrode containing said ferrous-ferric oxyhydroxy salt.

16. The material according to claim 1 , wherein said material is in the form of a film deposited on a metallic substrate of steel, copper, or an oxide thereof, or on a substrate of carbon, the film having a thickness of between about 0.1 μm and 0.1 mm.

17. The material according to claim 1 , wherein A n− represents carbonate or sulphate and a cell of said storage device comprises an acid electrolyte of sulphuric acid or hydrochloric acid.

18. The material according to claim 17 , wherein the potential difference (PD) of said cell of said storage device is from about 1 V to about 4 V.

19. The material according to claim 1 , wherein

D II is selected from the group consisting of Mg II , Ni II , Ca II , Mn II , Co II and Fe II , and

T III is selected from the group consisting of Al III , Co III , Cr III and Fe III .

20. An electrode for an energy storage device, comprising the material according to claim 1 .

21. The electrode according to claim 20 , wherein said energy storage device is an electric cell, a battery, an accumulator, or a supercapacitor.

22. A film deposited on a metallic substrate of steel, copper or an oxide thereof, or on a substrate of carbon, the film comprising the at least one compound of general formula (I), defined in claim 1 , the thickness of the film being between about 0.1 μm and 0.1 mm.

23. The film according to claim 22 , wherein A n− represents CO 3 2− .

24. The film according to claim 22 , configured to be used as cathode or anode of an energy storage device.

25. An energy storage device comprising the cathode or anode according to claim 24 .

26. The energy storage device according to claim 25 , further comprising an acid electrolyte of sulphuric acid or hydrochloric acid.

27. The energy storage device according to claim 26

the acid electrolyte is in the form of a gel or a solution, at a pH below 5.

28. A composite comprising the at least one compound of general formula (I), defined in claim 1 .

29. The composite according to claim 28 , further comprising a binder of oil or paraffin.

30. The composite according to claim 29 , wherein said binder is paraffin and said composite material comprises a carbon matrix mixed with the ferrous-ferric oxyhydroxy salt, the ferrous-ferric oxyhydroxy salt/carbon ratio (w/w) being from about 0.1 to about 100, and the ferrous-ferric oxyhydroxy salt/paraffin ratio (w/w) being from about 1 to about 10.

31. The composite according to claim 29 , wherein said binder is oil and said composite material comprises a carbon matrix mixed with the ferrous-ferric oxyhydroxy salt, the ferrous-ferric oxyhydroxy salt/carbon ratio (w/w) being from about 0.1 to about 100, and the ferrous-ferric oxyhydroxy salt/oil ratio (w/w) being from about 1 to about 10.