Rechargeable aluminum-air electrochemical cell

Abstract

The present invention relates to a secondary aluminum-air electrochemical cell. Therefore, the invention may be framed within the energy storage sector and, in particular, the sector of technologies and industries that require energy accumulators.

Claims

1. Secondary aluminum-air electrochemical cell comprising: a first positive electrode (3) and a second positive electrode (3) electrically connected to one another, to form the cathode (2); a negative electrode (5) that forms the anode (1), placed between the first positive electrode (3) and the second positive electrode (3); a first separation membrane (4) placed between the first positive electrode (3) and the negative electrode (5); a second separation membrane (4) placed between the second positive electrode (3) and the negative electrode (5); a non-aqueous electrolyte (7) that covers the first positive electrode (3), the second positive electrode (3), the negative electrode (5), the first separation membrane (4) and the second separation membrane (4); a micro-perforated housing (6) that comprises the first positive electrode (3), the second positive electrode (3), the negative electrode (5), the first separation membrane (4), the second separation membrane (4) and the electrolyte (7); where each positive electrode (3) comprises: a metal mesh; a gas diffusion layer, pressed into the metal mesh, selected from a pyrolytic graphite sheet or a non-woven carbon fabric; and a catalytic ink dispersed on the gas diffusion layer, wherein the catalytic ink comprises: a catalyst that comprises at least one metal oxide selected from ruthenium oxide RuO.sub.2, manganese oxide MnO.sub.2, iridium oxide IrO.sub.2, nickel oxide Ni.sub.2O.sub.3 and lanthanum oxide La.sub.2O.sub.3; a support for the catalyst based on reduced graphene oxide; and an alcoholic solution; where each separation membrane (4) has a pore size ranging between 60 and 90 pm, where the negative electrode (5) comprises aluminum.

2. Secondary electrochemical cell according to claim 1, wherein the metal mesh that is part of the positive electrode (3) is selected from a nickel mesh and a steel mesh.

3. Secondary aluminum-air electrochemical cell according to claim 1, wherein the catalyst that is part of the catalytic ink of the positive electrode (3) comprises manganese oxide (MnO.sub.2) and at least one metal oxide selected from ruthenium oxide RuO.sub.2, iridium oxide IrO.sub.2, nickel oxide Ni.sub.2O.sub.3 and lanthanum oxide La.sub.2O.sub.3.

4. Secondary aluminum-air electrochemical cell according to claim 3, wherein the catalyst that is part of the catalytic ink of the positive electrode (3) is manganese oxide (MnO.sub.2).

5. Secondary aluminum-air electrochemical cell according to claim 1, wherein the support for the catalyst that is part of the catalytic ink of the positive electrode (3) is composed of reduced graphene oxide nanoparticles.

6. Secondary aluminum-air electrochemical cell according to claim 1, wherein the alcoholic solution that is part of the catalytic ink of the positive electrode (3) is an isopropanol aqueous solution in a 3:1 ratio.

7. Secondary aluminum-air electrochemical cell according to claim 1, wherein the first and the second positive electrodes (3) have the same composition.

8. Secondary aluminum-air electrochemical cell according to claim 1, wherein the separation membrane (4) has a pore size ranging between 60 and 90 pm.

9. Secondary aluminum-air electrochemical cell according to claim 1, wherein the separation membrane (4) is made of polyethylene or polytetrafluoroethylene.

10. Secondary aluminum-air electrochemical cell according to claim 1, wherein the negative electrode (5) is selected from aluminum and an aluminum alloy that comprises at least one metal selected from Mg, Sn, Zn, In and Ga.

11. Secondary aluminum-air electrochemical cell according to claim 10, wherein the negative electrode (5) is an aluminum alloy that comprises at least one metal selected from Mg, Sn, Zn, In and Ga, and the weight percentage of the metal ranges between 0.1% and 2% with respect to the total weight of the aluminum alloy.

12. Secondary aluminum-air electrochemical cell according to claim 1, wherein the non-aqueous electrolyte comprises: an ionic liquid selected from an imidazolium salt, a pyrrolodinium salt, a phosphonium salt or a combination thereof; an organic solvent selected from propylene carbonate, dimethyl carbonate, tetrahydrofuran, acetonitrile or a combination thereof; and an aluminum salt selected from aluminum hexafluorophosphate, aluminum chloride, aluminum nitrate, aluminum isopropylate or a combination thereof.

13. Secondary aluminum-air electrochemical cell according to claim 12, wherein the non-aqueous electrolyte comprises an imidazolium salt as the ionic liquid.

14. Secondary aluminum-air electrochemical cell according to claim 12, wherein the organic solvent is selected from propylene carbonate, dimethyl carbonate or a combination thereof.

15. Secondary aluminum-air electrochemical cell according to claim 12, wherein the weight percentage of the organic solvent in the electrolyte ranges between 0.1% and 8% with respect to the total weight of the electrolyte.

16. Secondary aluminum-air electrochemical cell according to claim 12, wherein the aluminum salt is aluminum nitrate.

17. Secondary aluminum-air electrochemical cell according to claim 12, wherein the weight percentage of the aluminum salt in the electrolyte ranges between 1% and 5% with respect to the total weight of the electrolyte.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0081] FIG. 1 Diagram of the rechargeable aluminum-air electrochemical cell.

[0082] FIG. 2 Diagram of a positive electrode of the rechargeable aluminum-air cell.

[0083] FIG. 3 Cycling of the rechargeable aluminum-air battery at a symmetrical charge/discharge current of C/100 A.

EXAMPLES

[0084] Below we will illustrate the invention by means of assays performed by the inventors, which demonstrate the effectiveness of the product of the invention.

[0085] FIG. 1 shows a diagram of the composition of the rechargeable Al-air electrochemical cell, which comprises the following elements:

[0086] (1) Anode formed by a negative electrode (5)

[0087] (2) Cathode formed by two positive electrodes (3)

[0088] (3) Positive electrode the composition whereof is described below

[0089] (4) Polymer membrane with a pore size ranging between 60-90 pm

[0090] (5) Negative electrode formed by a high-purity aluminum sheet (5N)

[0091] (6) Micro-perforated housing with a perforation diameter ranging between 1 and 10 μm

[0092] (7) Electrolyte composed of an ionic liquid of the imidazolium, dimethyl carbonate and aluminum nitrate families.

[0093] FIG. 2 shows a diagram of a positive electrode of the rechargeable Al-air cell. Said positive electrode comprises an electron-collector nickel mesh (2) and a gas diffusion layer (1) made of non-woven carbon fabric pressed into the metal mesh (2). An alcoholic catalytic ink (3) formed by reduced graphene oxide (4) and an MnO.sub.2 catalyst (5) is dispersed on the gas diffusion layer, supported on the reduced graphene oxide (4).

[0094] FIG. 3 shows the cycling of the rechargeable aluminum-air battery, at a charge and discharge current of C/100 A, i.e. the number of amperes per 100 hours.

[0095] The battery potential starts at 2 volts and, during the first cycles, the solid electrode-electrolyte interphase is formed, wherein the electrolyte undergoes a half-reaction with the surface of the carbonaceous electrodes to form the so-called SEI (solid electrolyte interphase). During this process, part of the electrolyte is absorbed by the carbon. From this point onward, the battery potential becomes stabilised at about 1.5 V. The cycling of the cell remains stable for at least 200 cycles, with a coulombic efficiency greater than 75%.