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Title:
NAPHTHALENE BASED LITHIUM COMPOUNDS, A PROCESS FOR THEIR PREPARATION, THEIR USE AS SOLID ORGANIC CATALYST, AND THEIR USE IN RECHARGEABLE NON-AQUEOUS LITHIUM-AIR BATTERY CELLS
Document Type and Number:
WIPO Patent Application WO/2021/148836
Kind Code:
A1
Abstract:
The present invention relates to novel naphthalene-based compounds, to their process of preparation, and to their use as Solid Organic Catalysts (SOC) in lithium-air battery cells to promote oxygen reactions. The invention also concerns a lithium-air battery cell wherein the positive electrode comprises a SOC according to the invention, as well as a battery pack comprising several lithium-air battery cells according to the invention. The use of a battery pack according to the invention as a rechargeable battery for vehicles, such as electric vehicles and hybrid vehicles, electronic devices, and stationary power generating devices, is also part of the invention. Finally, the invention is directed at a vehicle, an electronic device, and a stationary power generating device, comprising a battery pack according to the invention.

Inventors:
RENAULT STEVEN (SE)
CARBONI MARCO (SE)
BARDE FANNY JEANNE JULIE (BE)
CASTRO LAURENT (BE)
POIZOT PHILIPPE (FR)
Application Number:
PCT/IB2020/000090
Publication Date:
July 29, 2021
Filing Date:
January 20, 2020
Export Citation:
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Assignee:
TOYOTA MOTOR EUROPE (BE)
CENTRE NAT RECH SCIENT (FR)
UNIV NANTES (FR)
RENAULT STEVEN (SE)
CARBONI MARCO (SE)
International Classes:
C07C51/41; C07C51/15; C07C63/38; C07C63/40; C07C309/47; C07F1/02; H01M4/38; H01M4/62; H01M12/08
Foreign References:
JP2006172588A2006-06-29
CN104752765A2015-07-01
US8652692B22014-02-18
US7282295B22007-10-16
US7491458B22009-02-17
EP1096591A12001-05-02
US20100266907A12010-10-21
Other References:
STÉVEN RENAULT ET AL: "A green Li-organic battery working as a fuel cell in case of emergency", ENERGY & ENVIRONMENTAL SCIENCE, vol. 6, no. 7, 1 January 2013 (2013-01-01), Cambridge, pages 2124, XP055730844, ISSN: 1754-5692, DOI: 10.1039/c3ee40878g
XIANG ZHAO ET AL: "Homo-Helical Rod Packing as a Path Toward the Highest Density of Guest-Binding Metal Sites in Metal-Organic Frameworks", ANGEWANDTE CHEMIE, vol. 57, no. 21, 22 May 2018 (2018-05-22), DE, pages 6208 - 6211, XP055732124, ISSN: 1433-7851, DOI: 10.1002/anie.201802267
LEE, ADV. ENERGY MATER., 2017, pages 1602417
QIAO ET AL., ACS ENERGY LETT., vol. 3, 2018, pages 463 - 468
GAO ET AL., NATURE MATERIALS, vol. 15, 2016, pages 882
GAO ET AL., NATURE ENERGY, vol. 2, 2017, pages 17118
CHEN ET AL., NATURE CHEMISTRY, vol. 5, 2013, pages 489
KUNDU ET AL., ACS CENT., SCI, vol. 1, 2015, pages 510 - 515
HASE ET AL., CHEM. COMMUN, vol. 52, 2016, pages 12151 - 12154
BEI-GNER ET AL., PHYS, CHEM. CHEM, PHYS., vol. 17, 2015, pages 31769 - 31779
JOURNAL OF MATERIAL CHEMISTRY A, vol. 3, 2015, pages 19177 - 19185
NATURE MATERIALS, vol. 10, 2011, pages 682 - 686
SONG ET AL., JOURNAL OF POWER SOURCES, vol. 77, 1999, pages 183 - 197
CROCE, ELECTROCHIMICA ACTA, vol. 46, 2001, pages 2457 - 2461
SWIERCZYNSKI ET AL., CHEM. MATER., vol. 13, 2001, pages 1560 - 1564
RENAULT ET AL., ENERGY & ENVIRONMENTAL SCIENCE, vol. 6, 2013, pages 2124 - 2133
HASE ET AL., CHEM. COMMUN., vol. 52, 2016, pages 12151 - 12154
BERGNER ET AL., PHYS. CHEM. CHEM. PHYS., vol. 17, 2015, pages 31769 - 31779
KUNDU ET AL., ACS CENT., SET., vol. 1, 2015, pages 510 - 515
Attorney, Agent or Firm:
MENA, Sandra et al. (FR)
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Claims:
CLAIMS

1. A compound of formula (1) below: wherein:

- at least one of R1, R2, R3, R4, R5, R6, R7, or R8, is a group A comprising a permanent negative charge selected from the group consisting of (thio)carboxylate, (thio)sulfonate, (thio)phosphonate, sulfate, and amidate groups,

- at least one of R1, R2, R3, R4, R5, R6, R7, or R8, is a group B selected from the group consisting of -OLi, nitroxide, C1-C20-alkyl nitroxide, thio-C1-C20- ether, C1-C20-alkyl disulfide, C3-C20-aryl disulfide, C1-C20-alkylamine, and C3-C20-arylamine groups,

- the others R1, R2, R3, R4, R5, R6, R7, or R8, being selected from the group consisting of: H, aryl, alkyl, alkenyl, alkaryl, alkyloxy, aryloxy, amino- alkyl, amino-aryl, thio-alkyl, thio-aryl, alkyl phosphonate, aryl phosphonate, cyclodlenyl, -OCR, -(O=)CHNR, -HN(O=)CR, -(O=)COR, - HN(O=)CHNR, -HN(O=)COR, -(HN=)CHNR, -HN(HN=)CHNR, - (S=)CHNR, -HN(S=)CHNR, with R being H or a C1-C19-alkyl group, and preferably with R being H or a C1-C6-alkyl group, said R1, R2, R3, R4, R5, R6, R7, or R8 groups comprising from 1 to 20 carbon atoms and being optionally substituted with at least one halogen, oxygen or sulphur atom,

- at least one of R1, R2, R3, R4, R5, R6, R7, or R8, comprises at least one lithium ion, the number of lithium Ions being the same as the number of groups A comprising a permanent negative charge in order to render the compound of formula (I) globally neutral.

2. A compound according to claim 1, wherein at least two R1, R2, R3, R4, R5, R6, R7, or R8, are groups A comprising a permanent negative charge selected from the group consisting of (thio)carboxylate, (thio)sulfonate, (thio)phosphonate, sulfate, and amidate groups.

3. A compound according to claim 1 or claim 2, wherein at least two R1, R2, R3, R4, R5, R6, R7, or R8, are groups B selected from the group consisting of -OU, nitroxide, alkyl nitroxide, thioether, disulfide, alkylamine, and arylamine.

4. A compound according to claims 1 to 3, wherein R1, R2, R5, and R6, are hydrogen atoms.

5. A compound according to claims 1 to 4, wherein said compound is selected from the group consisting of:

20

6. A compound according to claim 5, wherein said compound is tetra lithium salt of 1,5-dihydroxy-2,6-naphthalenedicarboxylic acid (Li4DHNDC) of formula:

7. A process for the preparation of a compound of formula (1) according to claims 1 to 6, comprising the step of reading a naphthol with MeOLi or LiH (lithiation step) in stoichiometric amount, and under inert atmosphere.

8. A process according to claim 7 for the preparation of tetra lithium salt of 1,5-dihydroxy-2,6-naphthalenedlcarboxylic acid (Li4DHNDC) according to claim 5, according to the following reaction scheme:

9. Use of a compound of formula (1) according to claims 1 to 6, as a Solid Organic Catalyst (SOC) in a lithium-air battery cell.

10. A Solid Organic Catalyst (SOC) comprising a compound of formula (1) according to claims 1 to 6.

11. A Solid Organic Catalyst (SOC) according to claim 10, in the form of lamellar particles.

12. A Solid Organic Catalyst (SOC) according to claim 10 or claim 11, having a specific surface area greater than or equal to 5 m2.g-1.

13. A lithium-air battery cell comprising: a negative electrode containing a negative-electrode active material, a positive electrode using oxygen as a positive-electrode active material, and a non-aqueous electrolyte medium arranged between the negative electrode and the positive electrode, wherein the positive electrode comprises a Solid Organic Catalyst (SOC) of formula (1) according to claims 10 to 12.

14. A lithium-air battery cell according to claim 13, wherein the positive electrode further comprises carbon.

15. A lithium-air battery cell according to claim 13 or claim 14, wherein the weight ratio between carbon and the Solid Organic Catalyst (SOC) is 7:2.

16. A lithium-air battery cell according to claims 13 to 15, wherein the positive electrode further comprises a polymer binder selected from the group consisting of: polyethylene, polypropylene, polytetrafluoroethylene (PTFE), styrene-butadiene rubber, tetrafluoroethylene-hexafiuoropropylene copolymers, tetrafluoroethylene-hexafluoropropylene copolymers (FEP), tetrafluoroethylene- perfluoroalkyl vinyl ether copolymers (PFA), vinylidene fluoride- hexafluoropropylene copolymers, vinylidene fluoride-chlorotrifluoroethylene copolymers, ethylene-tetrafluoroethylene copolymers (ETFE resins), polychlorotrifluoroethylene (PCTFE), vinylidene fluoride-pentafluoropropylene copolymers, propylene-tetrafluoroethylene copolymers, ethylene- chlorotrifluoroethylene copolymers (ECTFE), vinylidene fluoride- hexafluoropropylene-tetrafluoroethylene copolymers, vinylidene fluoride- perfluoromethyl vinyl ether-tetrafluoroethylene copolymers, ethylene-acrylic acid copolymers, and copolymers having sulfonate group-terminated perfluorovinyl ether groups attached to a poly(tetraf!uoroethylene) backbone, and preferably polytetrafluoroethylene (PTFE).

17. A lithium-air battery cell according to claim 16, wherein the weight ratio between the polymer binder and (Solid Organic Catalyst (SOC) + carbon + polymer binder) is lower than or equal to 20%.

18. A lithium-air battery cell according to claims 14 to 17, wherein the non-aqueous electrolyte medium comprises one or more aprotic organic solvents selected from the group consisting of: chain carbonates, cyclic ester carbonates, chain ethers, cyclic ethers, glycol ethers, and nitrile solvents, and preferably glycol ethers such as tetraethylene glycol dimethyl ether (TEGDME).

19. A battery pack comprising at least two assembled lithium-air battery cells according to any of claims 14 to 18. 20. Use of a battery pack according to claim 19 as a rechargeable battery for electric vehicles and hybrid vehicles, electronic devices, and stationary power generating devices.

21. A vehicle, an electronic device, and a stationary power generating device, comprising a battery pack according to claim 19.

Description:
NAPHTHALENE BASED LITHIUM COMPOUNDS, A PROCESS FOR THEIR PREPARATION, THEIR USE AS SOLID ORGANIC CATALYST, AND THEIR USE IN RECHARGEABLE NON-AQUEOUS LITHIUM-AIR BATTERY CELLS

Field of the Invention

The present invention relates to novel naphthalene-based compounds, to their process of preparation, and to their use as Solid Organic Catalysts (SOC) in lithium-air battery cells to promote oxygen reactions. The invention also concerns a lithium-air battery cell wherein the positive electrode comprises a SOC according to the invention, as well as a battery pack comprising several lithium-air battery cells according to the invention. The use of a lithium-air battery cell according to the invention as a rechargeable battery for vehicles, such as electric vehicles and hybrid vehicles, electronic devices, and stationary power generating devices, is also part of the invention. Finally, the invention is directed at a vehicle, an electronic device, and a stationary power generating device, comprising a battery pack according to the invention.

Technological background

Rechargeable lithium batteries are of considerable interest due to their high energy density and high power. Especially, rechargeable lithium-air batteries have attracted attention for electric vehicles and hybrid vehicles, where high energy density is required. Lithium-air battery cells are used In various devices (such as computers and telephones), in automotive or stationary applications, and can be assembled in battery packs.

Rechargeable lithium-air batteries use oxygen in the air as a cathode active material. Therefore, compared to conventional lithium rechargeable batteries containing a transition metal oxide (e.g. lithium cobaltate), as a cathode active material, rechargeable lithium-air batteries are able to have larger capacity.

In metal-air batteries, the cathode active material, oxygen, is not contained within the battery. Instead, this material is provided by the surrounding atmosphere. Naturally, such a system allows in principle a very high specific energy (energy provided by the battery per unit weight, typically given in Wh/kg in this technical field). In such batteries, oxygen may be partially reduced to peroxide, or fully reduced to hydroxide or oxide depending on the catalyst, electrolyte, availability of oxygen, etc. When the negative electrode (anode) is lithium (Li), lithium peroxide (Li 2 O 2 ) or lithium oxide (Li 2 O) may be formed.

A lithium-air battery cell comprises in general the following parts:

- metal anode (e.g. containing Li),

- non-aqueous electrolyte (e.g. containing a lithium salt), and

- air cathode.

Other parts of the battery cell device may be present such as: current collectors on the anode and/or cathode side; a separator between the cathode- side electrolyte (catholyte) and anode-side electrolyte (anolyte); a barrier layer between a positive electrode (cathode) and electrolyte, or between a negative electrode (anode) and electrolyte.

Issues to be addressed in developing lithium-air battery cells include:

- avoiding the migration to the anode of soluble catalysts used at the positive electrode (cathode);

- lowering hysteresis by decreasing charging voltage and/or increasing discharge voltage of the lithium-air battery cell by avoiding degradation of electrolyte;

- increasing capacity of the lithium-air battery cell at a fixed rate.

To avoid migration of soluble catalysts at the anode, special separators may be used. Lee at al. (Adv. Energy Mater., 2017, 1602417) propose the use of glass fiber separators (GF/C, Whatman) coated with a polymer mixture of PEDOT:PSS [poly(3,4-ethylenedioxythiophene) polystyrene sulfonate] to avoid the migration of the soluble catalyst DMPZ (5,10-dihydro-5,10- dimethylphenazine) used for Oxygen Evolution Reaction (OER). Qiao et al. (ACS Energy Lett. 2018, 3, 463-468) suggest avoiding the shuttling of soluble catalysts to the U anode by using a special metal-organic framework (MOF)- based separator blocking the soluble species.

Gao et al. propose 2,5-Di-tert-Butyl-l,4-BenzoQuinone (DBBQ) as a soluble catalyst to increase the rate performances of a non-aqueous lithium-air battery cell. The air electrode is a Gas Diffusion Layer (GDL) based porous carbon electrode as air cathode. The anode is LiFePO 4 (Nature Materials, 2016, 15, 882) or Li protected by a Ohara glass necessitating the use of a two- compartment cell (Nature Energy, Vol. 2, 17118 (2017)), but Li metal cannot be used as anode because DBBQ would migrate to it and causes problem at the anode.

Chen et al., Nature Chemistry, 2013, 5, 489, report TetraThiaFulvalene (TTF) as a soluble catalyst and nano-porous gold as air cathode. Partially charged LiFePO 4 is used as anode.

Kundu et al., ACS Cent., Sci., 2015, 1, 510-515, use tris[4- (diethylamino)phenyl]amine (TDPA) as a soluble catalyst to promote the oxidation of UO 2 (charge process).

The major drawback of the solutions proposed by the prior art is the use of a soluble catalyst which does not permit the use of Li metal (without extra protection) as anode. Indeed, the migration of soluble catalysts at the anode deteriorates the lithium-air battery cell performances and safety, needing the use of additional features such as: a protection barrier to protect the Li metal from soluble catalysts contamination which can deposit at the surface of the Li metal and create nucleation site causing the formation of dendrites, special separators blocking the solute species, or specific cell design such as a two-compartment cell composed of two electrolyte compartments, i.e. one for the anode side and the other for the cathode side, to protect the Li anode. Hase et al., Chem. Commun. 2016, 52, 12151-12154, also use methoxy- 2,2,6,6-tetramethylpiperidine-1-oxyl (MeO-TEMPO) as soluble catalyst to enable the oxidation of Li 2 O 2 without parasitic reactions attributed to electrochemical charging. However, the TEMPO molecule needs to be chemically regenerated outside of the battery cell at the end of charge, which is not practical at all since the battery cell has to be refilled with new electrolyte after each charge.

Bergner et al., Phys. Chem. Chem. Phys., 2015, 17, 31769-31779, relate the use of nitroxides catalysts such as l-methyl-2-azaadamantane-N-oxyl (1- Me-AZADO). However, these nitroxides have the disadvantage of being soluble in the electrolyte, thus deteriorating the anode of lithium-air battery cells.

The present invention remedies to all the problems of the prior art by providing a novel naphthalene-based compound used as SOC in lithium-air battery cells, and which:

- increases the capacity of U-O 2 battery cell at a fixed rate,

- increases re-chargeability of Li-O 2 battery cell, and therefore the cydability of the battery cell,

- increases rate performances, which means the speed of (dis)charge of the battery cell, while retaining a decent capacity,

- allows a simpler battery cell design since the SOC of the invention is not soluble, and therefore does not need a lithium protective layer, a special separator, or a two-compartment cell,

- the SOC is self-regenerated inside the battery cell and returns to ib initial state,

- allows to decrease the amount of carbon used at the positive electrode (air cathode), and therefore avoid corrosion of carbon which is known as a source of poor re-chargeability. Indeed, carbon is well-known in lithium-air battery systems to corrode and lead to partial formation of Li 2 CO3 (side reaction discharge product) instead of Li 2 O 2 (ideal discharge product). In addition, the SOC of the invention is cost effective (compared to other catalysts used in lithium-air systems based on gold, platinum or cobalt oxides) and is an environmentally-friendly organic material that may be prepared from renewable resources (biomass).

Summary of the invention

The present invention, in one aspect, relates to a novel naphthalene- based compound of specific formula (1) as defined hereinafter.

The invention also concerns a process of preparation of such specific compound of formula (1).

The use of such specific compound of formula (1) as SOC in lithium-air battery cells is also part of the invention.

The invention also concerns a lithium-air battery cell comprising:

- a negative electrode (anode) containing a negative-electrode active material;

- a positive electrode (cathode) using oxygen as a positive-electrode active material; and

- a non-aqueous electrolyte medium arranged between the negative electrode and the positive electrode; wherein the positive electrode comprises the compound of formula (1) as

SOC.

In another aspect, the invention relates to a battery pack comprising several lithium-air battery cells according to the invention assembled together.

The invention also relates to the use of a battery pack according to the invention as a rechargeable battery for electric vehicles and hybrid vehicles, electronic devices, and stationary power generating devices.

Finally, the invention also relates to a vehicle, an electronic device, and a stationary power generating device, comprising a battery pack according to the invention. Brief description of the Figures

Figure 1 shows the ThermoGravimetric Analysis (TGA) of tetra lithium salt of 1,5-dihydroxy-2,6-naphthalenedicarboxylic acid (Li 4 DHNDC) obtained with (Fig. la) or without (Fig. lb) excess of lithium methoxide (MeOLi).

Figure 2 shows Fourier Transform Infrared Spectroscopy (FT-IR) spectra of precursor 1,5-dihydroxy-2,6-naphthalenedicarboxylic acid (H 4 DHNDC) (Fig. 2a) and Li 4 DHNDC (Fig. 2b).

Figure 3 represents the Scanning Electron Microscopy (SEM) pictures of Li 4 DHNDC.

Figure 4 shows the voltage (V versus Li + /Li) versus the capacity (mAh.cm -2 ) for a lithium-air battery cell cycled at 0.2 mAh.cm -2 as described in Example 1 (Exl) compared to Comparative Examples 1, 2 and 3 (CE1, CE2, CE3).

Figure 5 shows the cycling of the lithium-air battery cell (Fig. 5a) of Example 1 at 0.2 mAh.cm -2 rate, within the potential window 2.2 - 4.6 V versus Li + /Li and with a capacity limitation of 800 mAh.g -1 soc (~2.15 mAh.cm -2 ), and the capacity retention versus the cycle number (Fig. 5b) of Example 1.

Figure 6 shows a comparison of the 1 st cycle of the lithium-air battery cell of Example 1 using a working electrode containing Li 4 DHNDC as SOC obtained in argon (dotted line) or in oxygen (plain line) for electrodes containing a weight ratio of Carbon Super C65:Li 4 DHNDC of 7:2 (galvanostatic discharge performed at 0.5 mAh.cm -2 ),

Figure 7 Is a schematic view of a metal-air battery cell with one electrochemical cell inside a gas compartment (Fig. 7a) and a metal-air battery pack with several cells inside a gas compartment (Fig. 7b), with: 11: gas compartment (dry air or pure oxygen), 12: metal anode, 13: cathode, 14: electrolyte/separator, 15: anode current collector, and 16: cathode current collector. Detailed description of the invention

The present invention relates to a novel naphthalene-based compound of formula (1) below: wherein:

- at least one of R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7 , or R 8 , is a group A comprising a permanent negative charge selected from the group consisting of (thio)carboxylate, (thio)sulfonate, (thio)phosphonate, sulfate, and amidate (-C(-O)-N--) groups,

- at least one of R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7 , or R 8 , is a group B selected from the group consisting of -OLi, nitroxide (-N(O · )-), C 1 -C 20 -alkyl nitroxide, thio- C 1 -C 20 -ether, C 1 -C 20 -alkyl disulfide, C 3 -C 20 -aryl disulfide, C 1 -C 20 - alkylamine, and C 3 -C 20 -arylamine groups,

- the others R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7 , or R 8 , being selected from the group consisting of: hydrogen (H), aryl, alkyl, alkenyl, alkaryl, alkyloxy, aryloxy, amino-alkyl, amino-aryl, thio-alkyl, thio-aryl, alkyl phosphonate, aryl phosphonate, cyclodienyl, -OCR, (O=)CHNR, -HN(O=)CR, -(O=)COR, - HN(O-)CHNR, -HN(O=)COR, ~(HN=)CHNR, -HN(HN=)CHNR, - (S=)CHNR, -HN(S-)CHNR, with R being H or a C 1 -C 19 -alkyl group, and preferably with R being H or a C 1 -C 6 -alkyl group, said R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7 , or R 8 groups comprising from 1 to 20 carbon atoms and being optionally substituted with at least one halogen, oxygen or sulphur atom,

- at least one of R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7 , or R 8 , comprises at least one lithium ion, the number of lithium ions being the same as the number of groups A comprising a permanent negative charge in order to render the compound of formula (I) globally neutral.

In the sense of the invention, the following terms mean:

Alkyl: a saturated, linear or branched, C 1 -C 20 , preferably C 1 -C 12 , more preferably C 1 -C 6 , and even more preferably C 1 -C 4 , hydrocarbon-based aliphatic group. The term "branched" means that at least one lower alkyl group such as methyl or ethyl is carried by a linear alkyl chain. As the alkyl group, there may be mentioned, for example, methyl, ethyl, n-propyl, i-propyl, n-butyl, t-butyi, i-butyl, s-butyl and n-pentyl;

Aryl: any functional group or substituent derived from at least one aromatic ring; an aromatic ring corresponds to any planar mono- or polycyclic group comprising a delocalized π-system in which each atom of the cycle comprises a p-orbital, said p-orbital overlapping each other; among such aryl groups there may be mentioned phenyl, biphenyl, naphthalene and anthracene groups. The aryl groups of the invention preferably comprise from 4 to 20 carbon atoms, even preferably from 4 to 12 carbon atoms, and even more preferably from 5 to 6 carbon atoms;

Alkenyl: a linear or branched, C 1 -C 20 , preferably C 1 -C 12 , more preferably C 1 -C 6 , and even more preferably C 1 -C 4 , unsaturated hydrocarbon- based aliphatic group that contains at least one carbon-carbon double bond. The term "branched" means that at least one lower alkyl group such as methyl or ethyl is carried by a linear alkenyl chain;

Alkaryl: any group derived from an alkyl group as defined above wherein a hydrogen atom is replaced by an aryl as defined above. The alkaryl preferably comprises from 5 to 20 carbon atoms, and more preferably from 5 to 12 carbon atoms;

Alkyloxy: a saturated, linear or branched, C 1 -C 20 , preferably C 1 -C 12 , more preferably C 1 -C 6 , and even more preferably C 1 -C 4 , hydrocarbon-based aliphatic group containing an oxygen atom. As the alkyl group, there may be mentioned, for example, methyloxy, ethyloxy, n-propyloxy, iso-propyloxy, n- butyloxy, sec-butyloxy, tert-butyloxy and isobutyloxy radicals;

Aryloxy: any ary] radical linked to an oxygen atom, preferably comprising from 4 to 20 carbon atoms, and more preferably from 4 to 12 carbon atoms. As the aryloxy group, it may be mentioned, for example, phenoxy radical;

Amino-alkyl: a saturated, linear or branched, C 1 -C 20 , preferably C 1 - C 12 , more preferably C 1 -C 6 , and even more preferably C 1 -C 4 , hydrocarbon-based aliphatic group bearing an amino group, and preferably a primary amino group -NH 2 ;

Amino-aryl: any aryl radical linked to an amino group, and preferably a primary amino group -NH 2 , preferably comprising from 4 to 20 carbon atoms, and more preferably from 4 to 12 carbon atoms;

Thio-alkyl: a saturated, linear or branched, C 1 -C 20 , preferably C 1 - C 12 , more preferably C 1 -C 6 , and even more preferably C 1 -C 4 hydrocarbon-based aliphatic group bearing a thiol group -SH;

Thio-aryl: any aryl radical linked to a thiol group -SH, preferably comprising from 4 to 20 carbon atoms, and more preferably from 4 to 12 carbon atoms;

Thio-ether: a saturated, linear or branched, C 1 -C 20 , preferably C 1 -C 12 , more preferably C 1 -C 6 , and even more preferably C 1 -C 4 , hydrocarbon-based aliphatic group bearing a functional group with the structure C-S-C;

Alkyl disulfide: a saturated, linear or branched, C 1 -C 20 , preferably C 1 -C 12 , more preferably C 1 -C 6 , and even more preferably C 1 -C 4 , hydrocarbon- based aliphatic group bearing a functional group with the structure C-S-S-C;

Alkyl phosphonate: any alkyl radical linked to a phosphonic group -P(=O)(OR') 2 wherein R' is a saturated, linear or branched, C 1 -C 20 , preferably C 1 -C 12 , more preferably C 1 -C 6 , and even more preferably C 1 -C 4 , hydrocarbon- based aliphatic group; Aryl phosphonate: any aryl radical linked to a phosphonate group -P(=O)(OR') 2 . wherein R' is saturated, linear or branched, C 1 -C 20 , preferably C 1 -C 12 , more preferably C 1 -C 6 , and even more preferably C 1 -C 4 , hydrocarbon-based aliphatic group;

Cyclodienyl: any unsaturated cyclic radical containing at least two carbon-carbon double bonds, and preferably comprising from 5 to 20 carbon atoms, and more preferably from 5 to 12 carbon atoms;

Alkyl nitroxide: a saturated, linear or branched, C 1 -C 20 , preferably C 1 -C 12 , more preferably C 1 -C 6 , and even more preferably C 1 -C 4 , hydrocarbon- based aliphatic group bearing an nitroxide radical -N(O . )-.

The presence of a group A comprising a permanent negative charge gives rise to lower the solubility of the compound of formula (1) in aprotic polar solvents.

In a preferred embodiment, in the compound of formula (1), at least two R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7 , or R 8 , are groups A comprising a permanent negative charge selected from the group consisting of (thio)carboxylates, (thio)sulfonates, (thio)phosphonates, sulfates, and amidates, and more preferably carboxylate groups.

In a preferred embodiment, in the compound of formula (1), at least two R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7 , or R 8 , are groups B selected from the group consisting of -OLi, nitroxide, alkyl nitroxide, thioether, disulfide, alkylamine, and arylamine, and more preferably -OLi.

In a preferred embodiment, the R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7 , or R 8 groups, others than groups A and B, are H. In a more preferred embodiment, R 1 , R 2 , R 5 , and R 6 , are H.

According to a preferred embodiment, the compound of formula (1) of the invention is selected from the group consisting of:

In a particularly preferred embodiment, the compound of formula (1) Is tetra lithium salt of 1,5-dihydroxy-2,6-naphthalenedicarboxylic acid (Li 4 DHNDC) of formula:

The present invention also relates to a process for the preparation of a compound Of formula (1) according to the invention, comprising the step of reacting a naphthoi with MeOLi in MeOH or LiH in DMF (lithiation step), and preferably MeOLi in MeOH, in stoichiometric amount, and under inert atmosphere (in a giovebox). The stoichiometric conditions are important to avoid having unreacted MeOLi mixed with the final compound of formula (1), the only remaining by-product when a complete conversion occurred being the solvent which is easily removed in vacuo.

In particular, the invention aims at a process for the preparation of Li 4 DHNDC according to the following reaction scheme:

The synthesis of H 4 DHNDC of the first step was already described in Journal of Material Chemistry A 2015, 3, 19177-19185.

In a second step, H 4 DHNDC is lithiated by MeOLi or LiH which is added under inert atmosphere and in stoichiometric amount in order to obtain Li 4 DHNDC. The second step is advantageously carried out in a protic solvent such as methanol, ethanol, isopropanol, n-propanol, n-butanol, ethylene glycol, and more advantageously methanol (MeOH).

The present invention also concerns the use of a compound of formula (1) of the invention as SQC in a lithium-air battery cell. The compound of formula (1) is a solid n-type electroactive organic catalyst lithium salt which may be used in lithium-air battery cells to promote oxygen reactions.

The invention also relates to a SOC comprising, and preferably consisting of, a compound of formula (1) according to the invention.

The SOC of the invention has the main advantage of not being soluble in electrolyte, avoiding the migration of soluble species to the anode. It further enhances the electrochemical performances of the reactions involving oxygen such as Oxygen Evolution Reaction (OER) and Oxygen Reduction Reaction (ORR), thus improving the capacity and re-chargeability of non-aqueous lithium-air battery cells.

The SOC of the invention is advantageously in the form of lamellar particles.

The SOC of the invention has advantageously a specific surface area greater than or equal to 5 m 2 .g -1 .

Another subject-matter of the present invention is a lithium-air battery cell comprising: a negative eiectrode (anode) containing a negative-electrode active material, a positive electrode (cathode) using oxygen as a positive-electrode active material, and a non-aqueous electrolyte medium arranged between the negative electrode and the positive electrode, wherein the positive electrode comprises a compound of formula (1) according to the invention as SOC.

Prior art 1 already discloses the synthesis of IMNQ and DANQ, those materials being used as active cathode materials in lithium-ion battery cells, which are closed battery systems, not In lithium-air battery cells. The main drawback of closed battery systems is their low capacity.

<Anode>

In the lithium-air battery cell of the present invention, the negative electrode (which may also be referred to as "anode" hereinafter) comprises at least an anode active material (which may also be referred to as "negative electrode active material" hereinafter). As the anode active material, general anode active materials for lithium batteries can be used and the anode active material is not particularly limited. In general, the anode active material is able to store/release a litiiium ion (Li + ). Specific anode active materials for rechargeable lithium-air batteries are, for example, a lithium metal, lithium protected anodes, lithium alloys such as a lithium-aluminum alloy, a lithium-tin alloy, a lithium-lead alloy and a lithium- silicon alloy, metal oxides such as a a lithium-titanium oxide, metal nitrides such as a lithium-cobalt nitride, a lithium-iron nitride and a lithium manganese nitride. Of these, lithium metal is preferred.

By "lithium-protected anode", reference Is made here for example (but is not limited to) to a "Lithium Protected Electrode" (LPE) as described in US 8,652,692. Usually the Li metal is covered by a solid electrolyte (for example LiSiCON (lithium superionic conductor) with formulae LiΜ 2 (ΡO 4 ) 3 ). Between the LiSiCON and the Li metal, there is usually an Interlayer (for example consisting of Cu 3 N/Li 3 N). In LPE systems, Li metal can be attached directly to one side of LiSiCON material, or alternatively a small amount of solvent containing a Li salt electrolyte may be added between the LiSiCON material and the Li metal to ensure U ionic conductivity. Such materials have been described in, for example, US 7,282,295 and US 7,491,458. LiSiCON materials have also been described in Nature Materials, 10, 682-686 (2011).

When a metal, alloy or the like in the form of foil or metal is used as the anode active material, it can be used as the anode Itself.

The anode is required to contain at least an anode active material; however, as needed, it can contain a binder for fixing the anode active material. The type and usage of the binder are the same as those of the air cathode described hereinafter.

An anode collector may be connected to the anode, which collects current from the anode. The material for the anode collector and the shape of the same are not particularly limited. Examples of the material for the anode collector include stainless steel, copper and nickel. Examples of the form of the anode collector include a foil form, a plate form and a mesh (grid) form. <Cathode>

In the lithium-air battery cell of the present invention, the positive electrode (which may also be referred to as "cathode" hereinafter) comprises at least a cathode active material (which may also be referred to as "positive electrode active material" hereinafter).

In the lithium-air battery cell of the present invention, the positive electrode uses oxygen as a positive-electrode active material. Oxygen serving as the positive-electrode active material may be contained in air or oxygen gas.

<Catalyst>

In the lithium-air battery cell of the present invention, the catalyst present in the positive electrode is a SOC of formula (1),

The SOC of formula (1) of the invention advantageously shows less than 150 g.L -1 solubility In lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) 1M in tetraethylene glycol dimethyl ether (TEGDME).

Additionally to the compound of formula (1), the positive electrode of the lithium-air battery cell of the invention may further comprise another SOC.

When additional SOC are present, the weight ratio between the SOC of formula (1) of the invention and the other SOC may range from 0.1/99.9 to 100/0, preferably from 60/40 to 40/60, and more preferably is of 50/50.

In the lithium-air battery cell of the present invention, the positive electrode may be a component in which the redox catalyst is supported on a carrier. An example of the carrier is carbon. Therefore, in the lithium-air battery cell of the invention, the positive electrode advantageously further comprises carbon. Examples of carbon include carbon blacks, such as Ketjen Black, acetylene black, channel black, furnace black, lamp black, and thermal black; graphite, such as natural graphite, e.g., scaly graphite, artificial graphite, and expanded graphite; activated carbon from charcoal and coal; carbon foam; carbon fibers obtained by carbonizing synthetic Fibers and petroleum pitch- based materials; carbon nanofibers; molecular carbon such as fullerenes; and tubular carbon, such as carbon nanotubes. Modified carbons such as N-doped carbon may also be used.

Positive electrode materials can also be used in a lithium-air battery cell of the present invention based on materials other than carbon. For example, positive electrode materials based on metal foam, stable and conductive metal oxides, or steel, can be used.

In the present invention, where carbon is used, it is preferably a porous material in the form of a powder and preferably has a high specific surface area of 20 to 2000 m 2 .g -1 , more preferably of 60 to 2000 m 2 .g -1 , and even more preferably of 60 to 1500 m 2 .g -1 For example, carbon may be used upon which a treatment is performed by a general method to increase porosity or surface area, followed by another treatment to increase the wettability. Different forms of carbon can be used in the present invention including SUPER P ® Li (from TIMCAL) showing a particle size of 40 nm and a specific surface area (determined by the Brunauer-Emmett-Teller method) of 62 m 2 .g -1 ; BLACK PEARLS® 2000 (from Cabot Corporation) showing a particle size of 12 nm and a specific surface area (determined by the Brunauer-Emmett-Teller method) of 1487 m 2 .g -1 ; Ketjen black® EC-600JD powder (from AzkoNobel) showing a specific surface area (determined by the Brunauer-Emmett-Teller method) of 1400 m 2 .g -1 . Examples of the commercial carbon products which can be used in the present invention include Carbon Super C65 (from Imerys), the KS series, SFG series, and Super S series (from TIMCAL), activated carbon products available from Norit and AB-Vulcan 72 (from Cabot). Other examples of commercially available carbon include the WAC powder series (from Xiamen All Carbon Corporation), PW15-type, 3-type, and S-type Activated Carbons (from Kureha), and Maxsorb MSP-15 (from Kansai Netsu Kagaku).

Examples of the method for increasing the porosity, surface area and wettability of the carbon include physical activation or chemical activation. The chemical activation method includes, for example, immersing the carbon material in a strong alkaline aqueous solution (potassium hydroxide solution for example), in an acid solution (nitric acid or phosphoric acid for example) or in a salt (zinc chloride for example). This treatment can be followed (but not necessarily) by a calcination step at relatively low temperature (450 to 900°C for example).

In addition, the carbon preferably has pores having a pore diameter of 5 nm or more, preferably of 20 nm or more. The specific surface area of the carbon and the pores size can be measured by the BET method or the BJH method, for example. Furthermore, in general, the carbon preferably has an average particle diameter (primary particle diameter) of 8 to 350 nm, more preferably of 30 to 50 nm. The average primary particle diameter of the carbon can be measured by TEM.

In the lithium-air battery cell of the invention, the weight ratio between carbon and the SOC of formula (1) of the invention is advantageously 7:2. When another SOC is present, the weight ratio between carbon : SOC of formula (1) of the invention : additional SOC (carbon:SOCl:SOC2) is advantageously 7:1:1.

In the lithium-air battery cell of the present invention, the positive electrode may contain a conductive material, in addition to the carbon and non- carbon materials discussed above. Examples of such further conductive materials include conductive fibers such as metal fibers; metal powders, such as silver, nickel, aluminium powders; and organic conductive materials such as polyphenylene derivatives. These may be used separately or in combination as a mixture.

In the lithium-air battery cell of the present invention, the positive electrode may contain a polymer binder. The polymer binder is not particularly limited. The polymer binder may be composed of a thermoplastic resin or a thermosetting resin. Examples thereof include polyethylene, polypropylene, polytetrafluoroethylene (FIFE), styrene-butadiene rubber, tetrafluoroethylene- hexafluoropropylene copolymers, tetrafiuoroethylene-hexafluoropropylene copolymers (FEP), tetrafluoroethylene-perfiuoroalkyl vinyl ether copolymers (PFA), vinylidene fluoride-hexafluoropropylene copolymers, vinylidene fluoride- chlorotrifluoroethylene copolymers, ethylene-tetrafluoroethylene copolymers

(ETFE resins), polychlorotrifluoroethylene (PCTFE), vinylidene fluoride- pentafluoropropylene copolymers, propylene-tetrafluoroethylene copolymers, ethylene-chlorotrifluoroethylene copolymers (ECTFE), vinylidene fluoride- hexafluoropropylene-tetrafluoroethylene copolymers, vinylidene fluoride- perfluoromethyl vinyl ether-tetrafluoroethylene copolymers, ethylene-acrylic acid copolymers. Copolymers having sulfonate group-terminated perfluorovlnyl ether groups attached to a poly(tetrafluoroethylene) backbone, such as those commonly referred to as Nafion ® , may also be envisaged as polymer binders in the present invention. These polymer binders may be used separately or in combination as a mixture. Polytetrafluoroethylene (PTFE) is a particularly preferred polymer binder.

In the lithium-air battery cell of the invenbon, the weight ratio between the polymer binder and (SOC of formula (1) + carbon + polymer binder) is lower than or equal to 20%. When another SOC is present, the proportion of binder remains constant and the weight ratio between the polymer binder and (SOC of formula (1) + additional SOC + carbon + polymer binder) remains lower than or equal to 20%.

In general, in advantageous embodiments of the present invention, an air cathode collector is connected to the air cathode, which collects current from the air cathode. The material for the air cathode collector and the shape of the same are not particularly limited. Examples of the material for the air cathode collector include stainless steel, aluminium, iron, nickel, dtanium and carbon. Examples of the form of the air cathode collector include a foil form, a plate form, a mesh (grid) form and a fibrous form. Preferably, the air cathode collector has a porous structure such as a mesh form since the collector having a porous structure has excellent efficiency of oxygen supply to the air cathode.

In some embodiments, the air electrode (air cathode) further comprises hydrophobic hollow fibers. A hydrophobic fiber tends to generate a space between itself and the electrolyte. These spaces facilitate oxygen diffusion in the air electrode, enabling a thicker electrode to be used. Typically carbon- based air electrodes are 0.5 to 0.7 mm thick. Addition of hydrophobic fibers allows use of electrodes that are at least 1 mm thick. Suitable fibers include DuPont HOLLOFIL ® (100% polyester fiber with one more holes in the core), goose down (very small, extremely light down found next to the skin of geese), PTFE fiber, and woven hollow fiber doth, among others. KETJENBLACK® carbon can also be coated on these fibers.

<Electrolyte>

In the lithium-air battery cell of the present invention, the non-aqueous Ion-conducting (electrolyte) medium arranged between the negative electrode and the positive electrode is a non-aqueous electrolytic solution containing one or more organic solvents and typically containing a salt. Non-limiting examples of the salt that can be used include known supporting electrolytes, such as LiPF 6 , LiCIO 4 , LIAsF 6 , LiBF 4 , Li(CF 3 SO 2 ) 2 N (LiTFSI), LIFSI, LKCF 3 SO 3 ) (LiTriflate), LiN(C 2 F 5 SO 2 ) 2 , LiBOB, LIFAP, LIDMSI, LIHPSI, LIBETI, LiDFOB, LIBFMB, LiBison, LiDCTA, LiTDI, LiPDL These salts may be used separately or in combination. The concentration of the salt Is preferably in the range of 0.1 to 2.0 M, and more preferably of 0.8 to 1.2 M.

The lithium salts are appropriately used in the electrolyte medium in combination with aprotic organic solvents known for use in lithium-air batteries. Examples of such aprotic organic solvents include chain carbonates, cyclic ester carbonates, chain ethers, cyclic ethers, glycol ethers, and nitrile solvents. Examples of chain carbonates include dimethyl carbonate, diethyl carbonate, and methyl ethyl carbonate. Examples of cyclic ester carbonates include γ- butyrolactone and γ-valerolactone. Examples of chain ethers include dimethoxyethane and ethylene glycol dimethyl ether. Examples of cyclic ethers include tetrahydrofuran and 2-methyltetrahydrofuran. Examples of glycol ethers include tetraethylene glycol dimethyl ether (TEGDME), diethylene glycol dimethyl ether (diglyme), triethylene glycol dimethyl ether (triglyme), polyethylene glycol) dimethyl ether with a weight average molecular weight Mw from 90 to 225 g.mol -1 . Nitrile solvents can also be used, such as acetonitrile, propionltrile, and 3-methoxypropionitrile. These aprotic organic solvents may be used separately or in combination as a mixture. Glycol ethers are the preferred aprotic organic solvents, and in particular tetraethylene glycol dimethyl ether (TEGDME).

In the framework of the present invention, gel polymer electrolytes can also be used. The gelled electrolyte having lithium ion conductivity can be obtained by, for example, adding a polymer to the non-aqueous electrolytic solution for gelation. In particular, gelation can be caused by adding a polymer such as polyethylene oxide (PEG), polyvinylidene fluoride (PVDF, commercially available as Kynar, etc,), polyacrylonitrile (PAN), polymethyl methacrylate (PMMA), and poly(vinyl) chloride (PVC). A review of the use of gel-type polymer electrolytes for lithium-ion batteries is provided by Song et al., Journal of Power Sources, 77(1999), 183-197.

Components which can be cross-linked and/or thermoset may also be added to the gel electrolyte formulation to improve its mechanical properties.

Also, incorporation of substantial amount of plasticizers (PEG, crown ethers, etc.) may be carried out to improve the ionic conductivity of the polymer electrolytes.

In addition, nanopart!cles/ceramics (AI 2 O 3 , SiO 2 , ZrO 2 , MgO, CeO 2 , etc.) may be added to such gel polymer electrolytes to increase their conductivities. Reference in this regard may be made to EP 1 096 591 A1 or Croce et a!., Electrochimica Acta 46 (2001), 2457-2461.

The nanoparticle/ceramic filler content is usually less than 10 wt% of the membrane. For example AI 2 O 3 nanoparticles may be obtained from Aldrich Research Grade and have 5.8 nm particle size (Swierczynski et al., Chem. Mater., 2001, 13, 1560-1564). SiO 2 fumed silica may be obtained from Aldrich Reagents Grade, with a 7 nm particle size. In general, the nanopartide size is preferentially around 15 nm or below.

It may further be contemplated In the framework of the present invention to add an oxygen dissolution enhancer to the electrolyte medium. This oxygen dissolution enhancer may be a fluorinated polymer, a fluorinated ether, a fluorinated ester, a fluorinated carbonate, a fluorinated carbon material, a fluorinated blood substitute, or indeed a metalloprotein. Such oxygen dissolution enhancers are described in US 2010/0266907.

<Separator>

In the rechargeable lithium-air battery cell of the present invention, a separator may advantageously be provided between the air cathode and the anode for complete electrical insulation between these electrodes. The separator is not particularly limited as long as it is able to electrically insulate the air cathode and the anode from each other and has a structure that allows the electrolyte to be present between the air cathode and the anode.

Examples of the separator include porous films and nonwoven fabrics comprising polyethylene, polypropylene, cellulose, polyvinylidene fluoride, glass ceramics, etc. Of these, a separator of glass ceramics is preferred.

< Battery cell case>

As the battery cell case for housing the rechargeable lithium-air battery cell, general battery cases for rechargeable lithium battery cell can be used. The shape of the battery cell case is not particularly limited as long as it can hold the above-mentioned air cathode, anode and electrolyte. Specific examples of the shape of the battery cell case include a coin shape, a flat plate shape, a cylindrical shape and a laminate shape. It is possible for the battery of the present invention to be completely encased in an oxygen-permeable membrane, advantageously one which shows selectivity for oxygen diffusion over that of water.

<Use of the battery cell of the invention>

The rechargeable lithium-air battery cell of the invention can discharge when an active material, which is oxygen, is supplied to the air cathode. Examples of oxygen supply source include the air and oxygen gas, and preferred is oxygen gas. The pressure of the supplied air or oxygen gas is not particularly limited and can be appropriately determined.

The lithium-air battery cell of the present invention may be used as a primary battery cell or a rechargeable secondary battery cell.

The lithium-air battery cell of the present invention may, for example, be put to practical use in a process wherein the battery is cycled between certain limits defined by initial and final voltage, or initial and final capacity or specific capacity. For example, one process for using the lithium-air battery cell of the present invention may consist of a process wherein:

(a) the lithium-air battery cell is provided in a fully charged state;

(b) the lithium-air battery cell is subjected to discharge until the specific capacity reaches a value X;

(c) the lithium-air battery cell is recharged;

(d) steps (b) and (c) are repeated.

The specific capacity value X selected may vary widely and, for example, be situated in the range of 200 to 10000 mAh.g -1 . The specific capacity of a lithium-air battery cell may be determined by discharging up until 2 V. It may be appropriate during operation of the battery cell to cycle the battery cell within limits that do not go to full discharge or charge. It may be advantageous to cycle the battery cell from 10 to 90% of its specific capacity (determined in step (b)), preferably from 20 to 80%, and more preferably from 20 to 70%. Cycling may also be carried out between certain limits of initial or maximum theoretical discharge capacity. Capacity-limited cycling may enable the cell to survive longer, and it may thus be appropriate to limit the cycling capacity to around 30% of the full discharge capacity.

It is possible to provide as a product a battery cell whose air cathode contains added Li 2 O 2 Such a battery cell would typically be charged before use.

The lithium-air battery cell of the present invention can be used as a rechargeable lithium battery for electric vehicles and hybrid vehicles, electronic devices (such as computers and telephones), and stationary power generating devices, and can be assembled in battery packs. The number of battery cells may vary depending on the final use of the lithium-air battery, and preferably may vary from 2 to 250 battery cells. There are two possible ways to assemble battery cells depending on the final target: in parallel or in series. In parallel, the capacity of each cell is added while keeping the same voltage. In series, the voltage of each cell is added while the capacity is the one of the smallest cell.

Any combination of the above described elements in all possible variations thereof Is encompassed by the invention unless otherwise indicated herein or otherwise clearly contradicted by context. Thus, all features and embodiments described herein in particular as applicable, advantageous or preferred in the context of the invention are to be construed as being applicable In combination with one another, in preferred embodiments of the invention. Examples

Preparation of a SOC according to the invention: Li 4 DHNDC a) First step: Preparation of H 4 DHNDC

2.24 g (14 mmol) of 1,5-dihydronaphthalene and 4.2 g (42 mmol) of KHCO 3 were grinded together and introduced in a 45 mL Parr reactor along with 8 ml of 1,2,4-trichlorobenzene and 9 g of dry ice. The Parr reactor was sealed and heated at 250°C for 17 h. At room temperature (25°C), the resulting paste was washed with 80 mL of diethyl ether (Et 2 O) then dissolved in 1,5 L of ultrapure water. The solution was filtered, then acidified with a 12 N HCI solution resulting in the precipitation of a light green solid. The solid was filtered, washed abundantly with ultrapure water and dried.

2.81 g of a green powder are obtained (yield = 81 %).

ATR-IR: v max/cm -1 3210, 2975, 2844, 2596, 2532, 1650, 1598, 1490, 1438, 1415, 1296, 1237, 1209, 1189, 1167, 1013, 881, 826, 766, 743, 677 cm "

1.

1 H NMR: δ H (400 MHz, (CD 3 ) 2 SO) 7.77 (2H, d, J = 8.9 Hz), 7.69 (2H, d, J = 8.8 Hz), 4.06 (4H, broad); l 3 C NMR: δ c : (400 MHz, (CD 3 ) 2 SO) 173.1, 159.9, 128.2, 125.5, 113.7,

109.5. b) Second step: Preparation of Li 4 DHNDC

In a flat-bottom flask, 248.2 mg (1 mmol) of H4DHNDC previously prepared were dissolved in 8 mL of dry MeOH under inert atmosphere (in a glovebox). 1.82 mL (4 mmol) of a 2.2 M solution of MeOLi in MeOH (Aldrich) was added at room temperature (25°C). The mixture, initially a green solution, turned into a light brown/orange solution which slowly evolved into a dark brown/black solution. The mixture was stirred at room temperature (25°C) for 2 days until a suspension of a light brown powder was obtained. Superficial MeOH was eliminated in vacuo, and the obtained light brown powder was further dried in a Buchi oven in vacuo at 100°C for 15 h, and then at 150°C for 4 h. 271.7 mg of a light brown powder were obtained (quantitative yield).

ATR-IR: v max/cm -1 2942, 2846, 2791, 1567, 1531, 1482, 1426, 1385, 1268, 1230, 1187, 1164, 1078, 1025, 912, 833, 801, 767, 705, 658 cm 1 ;

1 H NMR: δ H (400 MHz, (CD^SO) 7.23 (2H, dd, J = 5.7, 3.4 Hz), 7.01 (2H, dd, J = 5.7, 3.4 Hz).

The characteristics of the obtained U4DHNDC were as follows:

- Specific surface area: 5.7 m 2 .g -1 , and

- Morphology: Lamellar particles.

Figure 1 shows the TGA of Li 4 DHNDC obtained with (Fig. la) or without (Fig. lb) excess of MeOLi, Figure 2 the FT-IR spectra of precursor H4DHNDC (Fig. 2a) and Li 4 DHNDC (Fig. 2b), and Figure 3 the SME pictures of Li 4 DHNDC.

Preparation of the electrolytes:

Three electrolyte solutions were prepared by dissolving: a) 1.0 M bis(trifluoromethane)sulfonimide lithium salt (LiTFSI, BASF) in TEGDME (Sigma Aldrich, moisture controlled grade), b) 1.0 M LiTFSI and 10 '2 M (10 mM) DBBQ (Sigma Aldrich) in TEGDME, c) 1.0 M LiTFSI and 10 '2 M (10 mM) TTF (Sigma Aldrich) in TEGDME. LiTFSI, DBBQ and TTF were dried at 1Q0°C overnight under vacuum while TEGDME solvent was used after drying/storage on regenerated 3 A molecular sieves (Sigma Aldrich) for at least 15 days in a glovebox. The water content in the solvent and in the electrolytes was determined by means 831KF Karl Fischer coulometer (Metrohm) technique and was measured to be lower than 4 ppm. Preparation of LiFePO 4 (LFP) anode: wt% composition: LFP/carbon black/binder (PVdF): 88/4.5/7.5 Expected loading: 1.3 mAh.cnrV 2 Expected loading: 9.89 mg tot .cm -2

Coating thickness (without aluminium foil): 47 pm Aluminium foil thickness: 15 pm (p Ai =2.7 g.cm *3 )

Coating porosity: 35%

Expected characteristics: Q reversible (@ C/5, potential window: 2.1 - 4.3 V) ~ 152 mAh.gLFP -1

The LFP electrodes used for the following tests are punched 11 mm diameter discs (area: 0.9503 cm 2 ).

The LFP electrodes were used as a counter electrode for all tests for standardization purposes.

Recorded voltages (Vvs LFP) were reported versus LI7U (Vvs u) according to the equation: Vvsu = 3.4V - Vvs LFP.

Preparation of the SOC electrode:

Pre-charging galvanostatic experiments of the SOC electrode were performed under argon utilizing metal Li as anode and an Arbin battery cycler. A constant current of 25 mA g -1 Li4DHNDC was applied up to a cut-off voltage of 4.0 V vs U7Li.

Assembly of the battery:

In order to compare the SOC of the invention to soluble catalysts (DBBQ andTTF) In the same experimental conditions, the tests were done in a configuration LFP/electrolyte/O 2 electrodes with a LFP anode.

Modified Swagelok cells with an opening to atmosphere were assembled using as anode a disc of pure lithium metal (diameter = 11 mm and thickness = 0.7 mm) or a disc of LFP (provided by IMN) (diameter = 11 mm, thickness = 0.045 mm, and 9.4 mg in weight of active material). Two pieces of glass fibre separators (Whatman, diameter = 13 mm) impregnated with 210 μL electrolyte were used as separators. The above prepared carbon- based electrodes were used as working electrodes. Before transferring the assembled Swagelok cells out of the glovebox, they were placed inside a special designed airtight container with inlet and outlet valves. Some Swagelok cells in the containers were kept under argon while the other containers were filled with a continuous relatively high flow of dry oxygen (5.0 purity, spilled from a high-pressure cylinder through a stainless steel gas lines) for 30 minutes. Similarly to the cathodes, LFP and separators were dried at 120°C overnight under vacuum and all the cell components (modified Swagelok and designed airtight containers) were dried in an oven at 70°C for 12 h before usage.

Comparative Example 1: Air electrode containing only carbon

(reference)

Carbon Super C65 (Imerys) and polytetrafluoroethylene (PTFE, 60 wt% dispersion in H 2 O, Sigma Aldrich) were mixed with a weight ratio of 4:1 w/w (carbon: PTFE) in a agate mortar for 20 minutes. The resulting black paste was wetted with 2-propanol (VWR International, 1.4 mL 2-propanol/gpaste ) in order to improve the mixing and malleability. Once a rubber-like composite was obtained, approximately 160 mg were placed on a 4x4 cm 2 area stainless steel mesh. The rubber-like composite was then pressed using a Teflon™ cylinder until the mesh was evenly covered by the black paste. The mesh was then placed between two aluminum foils and, by means a hydraulic press, a pressure of 35 MPa was applied for 30 seconds three times. Afterwards, it was dried in a ventilating oven for 1 h at 100°C and then cut into discs of diameter 4 mm. Before using the above prepared electrodes, they were dried at 150°C overnight under vacuum. The final weight of electrodes was 0.8 ± 0.1 mg after mesh weight subtraction and with a thickness of 0.32 ± 0 .04 mm.

This air electrode containing only carbon and PTFE was assembled in a battery with an electrolyte free of any soluble catalyst (electrolyte a)).

Comparative Example 2: Air electrode Containing carbon + 10 mM DBBQ added in the electrolyte

The air electrode containing carbon and PTFE was prepared according to the same protocol as in Comparative Example 1 and was assembled in a battery with electrolyte containing 10 mM DBBQ (electrolyte b)).

Comparative example 3: Air electrode containing carbon + 10 mM TTF added in the electrolyte

The air electrode containing carbon and PTFE was prepared according to the same protocol as in Comparative Example 1 and was assembled in battery with electrolyte containing 10 m M TTF (electrolyte c)).

Example 1: Air electrode containing carbon + Li 4 DHNDC (7:2 weight ratio) in electrolyte a) Li 4 DHNDC, Carton Super C65 and PTFE (dry powder, Oxford University) were first dried overnight at 120°C under vacuum.

Carbon Super C65 and Li 4 DHNDC (carbon:Li 4 DHNDC weight ratio = 7:2) were mixed in a mortar for 20 minutes. After that, PTFE were blended with the pastes in a weight ratio (carbon + Li 4 DHNDC):PTFE of 4:1 and approximately 2 mL of 2-propanol was added. All the components were mixed for additional 20 minutes in an agate mortar until the two obtained rubber- like composites appeared homogeneously black (weight ratio carbon: Li 4 DHNDC = 7:2) (total weight ratio: Carbon Super C65 : Li 4 DHNDC :PTFE = 28:8:9). Then, a small amount of the resulting composites was spread on pre- punched discs of stainless steel mesh of diameter- 4 mm. The discs were then placed between two aluminum foils and, finally, a pressure of 35 MPa was applied for 30 seconds three times. The above prepared electrodes were dried again at 120°C overnight under vacuum to remove any trace of 2- propanol. The final weight was 1.2 ± 0.2 mg after mesh weight subtraction.

Figure 4 shows the voltage (V versus Li + /Li) versus the capacity (mAh.cm -2 ) for a lithium-air battery cell cycled at 0.2 mAh.cm -2 as described in Example 1 (Exl) compared to Comparative Examples 1, 2 and 3 (CE1, CE2, CE3). Figure 4 demonstrates that the electrode containing Li 4 DHNDC (Exl) allows increasing the discharge capacity (mAh.cm -2 ) and to recharge the lithium-air battery cell with 100% efficiency thanks to a lower hysteresis, which is not the case for CE1, CE2, CE3.

Figure 5 shows the cycling of the lithium-air battery cell (Fig. 5a) of Example 1 (Exl) at 0.2 mAh.cm -2 rate, within the potential window 2.2 - 4.6 V versus Li + /Li and with a capacity limitation of 800 mAh.g -1 soc (~2.15 mAh.cm -2 ), and the capacity retention versus the cycle number (Fig. 5b) of Example 1.

Figure 6 shows a comparison of the 1 st cycle of the lithium-air battery cell of Example 1 using a working electrode containing Li 4 DHNDC as SOC obtained in argon (dotted line) or in oxygen (plain line) for electrodes containing a weight ratio of Carbon Super C65: Li 4 DHNDC of 7:2 (galvanostatic discharge performed at 0.5 mAh,cm -2 ). The vertical line indicates the theoretical capacity expected. Figure 6 demonstrates that the SOC alone does not have a high capacity, while under oxygen an effect on the capacity is dearly seen.

Comparison with Prior art catalysts:

The following table (Table 1) summarizes properties of SOC used in lithium-air battery cells described in the present invention as compared to the ones disclosed in the following prior art references discussed above:

- Prior art 1: Renault et al., Energy & Environmental Science, 2013, 6,

2124-2133,

- Prior art 2: Gao et al., Nature Materials, 2016, 15, 882,

- Prior art 3: Chen et al., Nature Chemistry, 2013, 5, 489,

- Prior art 4: Gao et al., Nature Energy, Vol. 2, 17118 (2017),

- Prior art 5: Hase et al., Chem. Commun. 2016, 52, 12151-12154,

- Prior art 6: Bergner et al., Phys. Chem. Chem. Phys., 2015, 17, 31769- 31779, and

- Prior art 7: Kundu et al., ACS Cent., Sci., 2015, 1, 510-515.

Table 1: